IETF has a Message Layer Security (MLS) group that has been working towards a wide variety of group encryption systems. I need to re-check but I thought it included "must have m of n total keys" capabilities.

https://messaginglayersecurity.rocks/

I'd especially love to hear replies from folks who think this is limited, or that there are better ideas about. MLS has prefigured as one of the ultra-important works in progress, that in my mind will draw a nice bow around a massive amount of these kinds of communication problems. But I could be over-expecting, could be missing things.