I had this feature on a Xiaomi phone that i had a few years ago. I could even set up the fingerprint reader to open a different profile depending on which finger i used.

Or loads a dummy profile and deletes other profiles without giving away what is happening.

Alternately, a user profile that isn't displayed anywhere, but accessible only through a specific PIN, maybe. Not sure how you'd explain the storage space either option used, however.

You can already have multiple independent users in graphene (maybe in stock android too idk). You have to switch them before the possible search though.