My google photos doesn't even seem to support facial recognition, maybe I turned it off somehow at some point, but it doesn't seem like google photos supports manually selecting a face (a face that isn't detected), which is something I use a ton with Immich, it is very convenient, even if a bit tedious if going through a backlog.

Annoyingly you can't create a person that way yet with immich, but that's where digikam helps.