i think a feature that would be pretty cool for a secure chat app is per-chat system requirements. for some chats, you don't care what device is used, but in others where you're being extra cautious, you could say "only allow loonicks and graphene os" or something. or maybe even "lock this chat to one device specifically."

this would be mostly to stop users in the chat from accidentally exposing information by loading and viewing it on a compromised device. as such, users would probably be able to override this and view the chat anyway if they accept the risk. for example, your thread model might consider "debloated windows" to be good enough.

note that i am not a security / #privacy expert or anything. i'm just some dummy. this might be dumb and stupid like me.