Afaik this is what MicroG does, though their aim is different. They mimic Google services responses so that the apps work without G proprietary libraries and se

Afaik this is what MicroG does, though their aim is different. They mimic Google services responses so that the apps work without G proprietary libraries and services but I don't think privacy is their stated goal (I'd love for someone to correct me if I'm wrong, not using MicroG myself).