I use the NFC Yubikey to store a PGP key, which can then be used with pass [1] + GPG on the desktop, and Password Store + OpenKeychain on Android. Works nicely. And if you choose to also keep the PGP key on the desktop, you don't need to carry the Yubikey.

[1] https://www.passwordstore.org

I use this setup, it's fantastic.

Do you know if it will work with a 5X running Copperhead OS (no gapps)? Ie. is the apk available?

It's on F-Droid, so probably: https://f-droid.org/repository/browse/?fdfilter=yubico&fdid=...

Oh, great! Thanks.

it worked for everything i was using it with. but same problem as the OP mentioned, i dont always have my keys on me so it just became annoying after a while having to the thing first