If it's life-changing, you definitely shouldn't keep it on Mycelium. I don't know if there's a maximum transaction size (other than the usual 100 kB), but if you're not in a terrible rush, you can just try at low fee. You may want to read
[Apr 2021] Fees are low, use this opportunity to Consolidate your small inputs!. As an educated guess, setting 7 sat/byte will mean your transaction will most probably confirm on Sunday. You may be able to go as low as 5 sat/byte, but that might be too low. Even if "cost is no concern", there's no need to waste it on fees
But if you insist on a fast confirmation, you'll have to set 70 sat/byte or more.
Would Mycelium have no problem sweeping this wallet and with this transaction in general or is it best to consider other options?
You can just try it. If it's too large, just send a lower amount.
You may want to look at
Forkcoins if you're holding old Bitcoins. It might be enough to cover your transaction fees.
It's not "in" Mycelium but on a paper wallet, so no worries there. It would only be on Mycelium when I scan the private key and execute the transaction to send to my Ledger address.
In a nutshell, you're saying that Mycelium is perfectly capable of handling this transaction and that it is a perfectly viable option. Again, I don't care if it costs me $3K in transaction fees as long as it is a solid option.
Electrum is becoming a non-starter for me as from what others say in the Bitcoin board, I need to create 3 different wallets in Electrum to handle all the derication paths of the inputs in this single wallet and then do an offline transaction with a usb stick and...
It's just beyond my technical capability.
Edit: Will Mycelium have any issue with 3 different formats/inputs contained in a single private key (like Electrum does apparently) or is it a sweep-and-go operation with Mycelium handling the technicalities?
Thanks so much! Can't tell you how much I appreciate the help with this!