Your hardware wallet's seed is generated randomly in the device itself, not by the manufacturer.
The only trust issue is if the hardware's RNG is bad or rigged which is never the case in genuine famous hardware wallets.

If your hardware wallet came with a pre-generated wallet or seed phrase, avoid using that device entirely.

hexvir isn't the OP  
From what I see, his reply is to give OP an alternative mempool explorer or blockexplorer site.

I don't know which site that shows "waiting to appear" so I have no idea, usually there'll be a result or none.
On a side note, there's no official mempool ('cause of the phrase "mempool site itself"), every node has its own and has their own set of rules. (usually the default)
So if the majority of the nodes don't have your transaction, chances that it's non-standard is high.

For broadcasting transactions, every site with push service has a Bitcoin node on its backend so it's all basically the same as sendrawtransaction command.

It's your mempool, it's still subjected to other node's mempool if your transaction will propagate.
Try to search its txid in blockexplorers; if it's not there, chances that it's only in your node is high. (or a few nodes)

No, it's used to add inputs to an existing transaction.
Mainly used for funding no input transactions created via createrawtransaction command.

Electrum is non-custodial and the 2FA service provider (TrustedCoin) don't have access to your 2FA wallet's other two master keys.
Also, your wallet files aren't saved online, it's in your PC or device's storage
so the only way that it's created as 2fa is if you or someone who have access to your PC have setup a 2fa wallet.
Or other reasons like you're using a fake Electrum wallet which can easily be detected by verifying its signature: https://bitcoinelectrum.com/how-to-verify-your-electrum-download/
Signature files for old versions can be downloaded here: https://download.electrum.org/ (find the correct '.asc' file for your wallet's version)

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The only way to spend from it is to have access to either two of the three master keys:
TrustedCoin has one, your wallet file has one and your seed phrase has two.

So you either need the "seed phrase" which you should've saved
or the wallet (and its password) plus the master key in TrustedCoin's server.

Regarding the latter, you can try to contact them to see if there's a chance to provide a new authenticator, use the email that you've used to setup the 2FA wallet.
but AFAIK, they do not usually entertain such requests
Link to FAQ: https://trustedcoin.com/#/faq#lost_authenticator
Link to Contact (read the note): https://trustedcoin.com/#/contact-us

Try signrawtransactionwithkey and fill the optional "prevtx" arg with the required script depending on the input(s).
More info about the command: https://bitcoincore.org/en/doc/24.0.0/rpc/rawtransactions/signrawtransactionwithkey/

It just happened that the result of Hash160 is always 160-bit so any data that you've hashed can be converted into an address.

Now, if it's pure coincidence, then you've discovered a collision (but only until you find the owner of that address to confirm that your and his inputs are different).
But the most possible scenario here is someone did the exact same thing.

You can't, and I highly doubt that there's an owner of that address. (someone who owns its private key)
If there's someone who claims it for some reason, ask him to provide a signed message.

Try to run "salvage" on a copy of that wallet using Bitcoin Core's bitcoin-wallet tool.
The result will depend on the deleted parts, if the (encrypted) master key is intact, it should be able to restore it to a usable state.

Follow this post to use the command:

If you don't know how to "cd" (change directory), simply type cd "path_to_the_directory" in your Command Prompt window, in this case bitcoin core's bin folder.
e.g. (Windows default): cd C:\Program Files\Bitcoin\bin

Okay, so you're talking about the 'History' tab.

Yes, the transactions from that list wont be omitted once spent.
The only thing you can do is to filter it by date (Wallet->History->Filter) but those will still be loaded in the background.

By saying "keys" did you mean "private keys"?

The only problem that I see is if that key from the MultiSig wallet is compromised the single sig will be as well.
Hackers are notorious for trying every address type in keys that they got their hands on.

Do you mean "Ledger Live"?
Clearing the cache should also clear the spent coins after it resynchronize.

Here's how to: https://support.ledger.com/hc/en-us/articles/4404381846929-Clear-cache-in-Ledger-Live

It just means that it's that "deep" in the blockchain;
in other words, it's included in the older blocks and there are +N number of blocks on top of where it's included.

For example, if your transaction in confirmed in block height 778,640 and then the next block is mined, it'll be 2 confirmations.
Blocks are getting mined round-the-clock so confirmations wont stop at 6.

I can't see any rule that prohibited necroposting.
For the unofficial rules, refer to this thread: Unofficial list of (official) Bitcointalk.org rules, guidelines, FAQ

And a few replies below, there's a related reply from the author regarding the topic:

Depends if it's off-topic.
Example in Technical Support board, I only see a few who necropost with the exact same issue.
Usually, it's only "similar", which should have been a posted as a new topic.

It must be Kangaroo (https://bitcointalk.org/index.php?topic=5244940.0).
Since its public key is made public by the author, the private key is now susceptible to "birthday attack" which Kangaroo is good at.
Same reason why those harder puzzles divisible by 5 are solved before the easier ones.

If you're wondering what "BIP" means, yes it's an acronym but not of a wallet.
It's one of the many "Bitcoin Improvement Proposals" (github link), the number next to it is set by the author, usually in numeric order or already reserved.

So if you see another "BIP-XX" in a comment, the author is talking about a proposal from the list above.

Normally it's not much of an issue in most wallets, unless we're taking about thousands of small payouts.
Yours is a unique case.

That setting will also save you some satoshi later when you need to spend your mining rewards.
Because it could cause you to pay more fee if you end up creating transactions with high number of inputs (higher transaction size).

Now that you mentioned it, it looks like OP is mining bitcoins based from his post history.

@Moeter81 most mining pools usually have a "minimum payment" setting. (or a similar name)
Setting a higher value will lessen your UTXO amount since the pool will only send once in a while.
(of course, your current UTXOs wont be affected by it)

If the other hardware wallet can't consolidate/send those as well, you can create an Electrum "cold-storage" set-up to consolidate the funds or send it to a new wallet.
It's as secure as a hardware wallet as long as the offline device is totally air-gap (wiki) and wiped entirely after you've done with the consolidation.
Alternatively and recommended, send the funds to a newly setup hardware device with a new seed phrase.
Tutorial: https://electrum.readthedocs.io/en/latest/coldstorage.html
Creating a wallet from BIP39 seed requires some additional steps like enabling "BIP39 seed" in the seed option, extend seed (if it has a passphrase)
and selecting the correct script type (no Taproot support yet) and derivation path for account 2+.

That's a start, you can use the passwords that you've tested as "tokens" and add a small number of random characters, typo check, etc.

If you find it hard to set-up a bruteforce hardware/software, try to contact www.walletrecoveryservices.com
Here's his Bitcointalk thread: https://bitcointalk.org/index.php?topic=240779.0
The service is quite popular but it costs a fraction of the recovered amount. (not upfront)

No, I said "a small portion", means just an extremely tiny percent of the total combination is still A LOT.

Okay, good luck!

Because of the reason written in the OP.
More inputs produce higher transaction size which makes the fee higher, so small inputs that can't be used alone in your typical transactions are recommended to be consolidated.
So if most of your coins have good amount, there's no need for consolidation.

Privacy issue is also covered in the OP.