I have a question about Bitcoin cold wallets

[dkbit98]

I'm not sure if a Ledger hardware wallet comes with a Bitcoin wallet pre-installed. If it needs the Ledger Live software, it may still work if you install that on an offline system.
I wouldn't worry about firmware updates for a device that never sees the internet.

Ledger is always changing shit around but I think they are now shipping wallets (from China) without any preinstalled apps but they are suggesting that you can install Bitcoin and other apps.
That means it's not possible to use it in offline computer, and I wouldn't even do that when there is Electrum wallet.
I did try installing Trezor Suite offline on Linux and it's working just fine, you only need to enable Bitcoin (or other supported coins) but you may need to install other software needed for app to run.

I guess there's not really a market for it, because it's not very convenient to use, but I'd like to see a hardware wallet that's truely designed to be used offline. It could for instance use a camera (or QR-code on it's screen) to transmit transaction data, and instead of USB use only a power cable. That way, you could have a hardware wallet that's also a cold wallet.

Keystone hardware wallet is designed to be used offline and they are using QR codes for sending transactions.
You can also make your own airgapped signing device using Raspberry Pi zero (version without wifi).

[Coinoplex]

I wouldn’t suggest doing what I have mentioned, you probably should consider the other methods written in your post from reputable users, but if for any reason Trezor Desktop app or Website gets shutdown, you can run everything locally, Trezor is fully open source. I am running trezor emulator on my linux device for testing purposes, of course that wont be safe as the computer is connected to the internet but it shows you that Trezor-Firmware can be installed and run in a compatible device not necessarily the Trezor device itself. You can literally buy a small device and flash the trezor firmware on that device etc I have seen an article somewhere about the steps a guy has taken to install trezor-firmware on his own made hardware wallet.

[Pmalek]

You can literally buy a small device and flash the trezor firmware on that device etc I have seen an article somewhere about the steps a guy has taken to install trezor-firmware on his own made hardware wallet.

The case doesn't have to look the same as the one for Trezor, but if you want to assimilate the looks of a Trezor One, you can follow the guide that dkbit98 mentioned in his thread Make your own Trezor Hardware wallet for under $40. Whether or not all the spare parts are still around for under $40, considering the inflation and the general chip shortage, is a topic for a different discussion.