Passkeys work on whatever platforms your passkey is compatible with. I store mine in my BitWarden vault which works on web/PC/mobile just fine.
Pocket ID is an OpenID Connect provider (basically OAuth), so it depends on whichever apps you're using having support for that.
Home Assistant does not natively support OIDC, but there is a community project in active development which aims to add support.
What's the gist of your "personal experiences with Beeper"?