> Some sites, once connected via passkey, make it all but impossible to connect in another way.

That's the issue I had with Okta a few years back. I used a password then later added a passkey through Bitwarden on my work laptop. Bitwarden hadn't yet implemented passkeys for mobile.

I went to authenticate through Okta on my work phone. It prompted me for the passkey. Since mobile passkeys didn't exist, I got stonewalled. I had to make a blood sacrifice just to get Okta to allow password access again.