Not normally, that wouldn't make much sense. It's easier to just say you signed an NDA and anyone with sense knows you're not allowed to talk about the work.

Yeah that's what we do, whisper lists for everyone who needs to do inter-section Comms. Everyone else is just in the discord channels. It's not perfect but it's worked for years now

We use it for additional comms in foxhole, can't be in multiple channels at once and we've got about 8 groups that need to communicate between each other

I'm still figuring out if I can just straight up block people from certain servers