I have installed recently GrapeheneOS for first time. Prob not very relevant but my device is a Pixel 7.

I have a couple of Yubikeys, one of them Yubikey 5 NFC, that I use to login ie in GitHub from Vanadium browser.

I can login to GitHub
(1) with username/password and U2F (in Yubikey) as 2FA. Please, see screenshot while trying to login, https://imgur.com/a/fCNWyUR
(2) or with passkey (without user/password) also stored inside my Yubikey. Please see attached screenshot login by passkey: https://imgur.com/a/JffLtMw

To isolate problems right now I'm using my Yubikey plugged directly to phone by USB, although I could use NFC. Once I see that it works by USB I will try NFC.

But the U2F and FIDO2 passkey seem not to be working. Please, have a look to attached screenshots.

Similar issue I have when I try to signin in Proton-Calendar app using my Yubikey U2F as 2FA. I am getting the warning "An error occurred". I think this error is very related to login in GitHub

Please, see my sandboxed Play Services settings, https://imgur.com/a/Krhzphm
and my Vanadium settings, https://imgur.com/a/9WW8Q11

PS: I can use Yubico-Authenticator app in GrapheneOS with no issues. In this app I can list the passkeys I have stored in. Among them I can see the GitHub passkey.

Thanks