(original commenter) I've gone ahead and reset the key entirely and re-enrolled Bitwarden. It appears the issue isn't with the PIN per-se, as I get pretty much the exact same thing without it. Any third-party implementation of Webauthn or FIDO2 works (For example the "FIDO / WebAuthn test" app on Play Store), however, authentication for apps and services most often revolves around Google's FIDO library (Firefox, Vanadium/Chromium use it), which fails to authenticate with various errors, also causing Google play services to crash. If you have a Pixel with GrapheneOS available, could you give it a try?