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There are other options for sure. But I feel this choice is more compatible with the masses in terms of "ease of use" and "user friendliness". Let's see what other options the future brings though... :)

a regular usb drive?

Yes, you can take any USB flash drive and you can use veracrypt or some other linux tools to encrypt it. Personally I recommend creating a live USB of your favorite linux distro, secure it to all hell, and keep your wallets there.

When you create the linux os, make sure to encrypt the entire system and you are all set!

Yes, you can get any USB drive or any kind of drive including MicroSD and you can encrypted with Veracrypt. USB drives are more versatile and easier to carry that's all.

Veracrypt is the offshoot of Truecrypt which was very effective encrypting any drive.