Maybe disable Windows Hello
If we want to disable Windows Hello and associated biometrics queries in Tor Browser it looks like we can patch various IsUserVerifyingPlatformAuthenticatorAvailable calls to always return false.
It seems like there was a bit of a refactor to wrap both Windows Hello as well hardware tokens like yubikeys(?) into the same authentication system so we need to take care to not break support for these.
See this patch: https://bugzilla.mozilla.org/show_bug.cgi?id=1508115 The library Mozilla is using to add Windows Hello support: https://github.com/Microsoft/webauthn