This is of interest to me. The "keypair as identity" aspect of blockchains has use cases outside of blockchains. Nostr obviously one, but e.g. passkeys and that whole Yubikey/FIDO2 thing are becoming relevant in the real world.

But things are too proprietary. I'm looking at SoloKey and NitroKey. Want to build my own FIDO2/PKCS11 device with some extras like some sort of UI via a small display and buttons.