btw, Matrix server requirements are much higher, and the client apps are less user-friendly
For example, arcanechat.me server has more than 1400 users and the server is using around 800MB of RAM, CPU is idle most of the time or really low usage, less than 3GB of disk (including whole Debian operative system etc)
I bet it is using more resources than my +1400 people server 😅 but yeah for 10 people it is probably OK with matrix as long as they don't join some crazy federated groups etc