Since there are a number of people interested now in aligning on Group impls, maybe this is the time to collectively start work on a design doc, before we have yet another 50+ comment inconclusive thread. And then - later on - possibly turn it into a FEP. There’s already a bunch of Requirements to be listed, and some design choices already made.
This may start with a wiki post here, or a HedgeDoc in public.cat, or directly with a FEP markdown + open issues.