Keychat is an app. It supports protocols and is open source but which other apps are compatible?
To my understanding, WN explored signal and MLS, too and decided to go with more advanced tools to be ...
White Noise is also just an app, from what I've gathered. Plus, when it comes to group chats, it seems to me that on the protocol level, Marmot it is trying to do the same thing that Keychat has already successfully done - facilitate large group chats using MLS with nostr relays as the transport layer. I might be totally wrong though - if so, I would be very grateful if you (or anyone else reading this) could point me to some resources explaining the difference.