Plex’s support doc claims there’s a limit of a single stream, but I don’t think that’s been accurate for a very long time.
https://support.plex.tv/articles/115002178853-using-hardware-accelerated-streaming/
There have been reports of 6+ simultaneous sessions on Apple M1 CPUs:
I don’t mean to distract from your question about the M2, and if it’s better than the M1 for this purpose. I’m curious as well.