However, with the above in mind and if I was buying right now, I really like the way Keystone is going, especially when it comes to the point of batteries issues over time.
I also like Keystone approach on many things, but I have my concerns and complains for them also.
For example, they are still not supporting Segwit addresses and Taproot support will come maybe in 2022 but just for Bitcoinonly firmare.
Second thing is that we don't exactly know what secure element they use because they never disclosed that information.
If you ask me, I am waiting to see first fully open source hardware wallet from Trezor, Square or maybe someone else who knows.
Lastly, no way I'd use Ledger for FIDO and I don't suggest anyone use any hardware wallet for that purpose either, simply because you're putting too many eggs in one basket if you ask me.
Adding FIDO 2FA is cool feature in theory, and it would be nice to use one device only for that, but my issue is what happens if device gets broken or firmware update messes up everything.
You can't use any backup on other FIDO devices and you must buy new ledger, or your can't log-in on your account anymore.