Close... Correction: You don't have to use Micro$oft 365.

See response to other user.

Element Server Suite, on the Matrix Network. Until Nostr is ready and capable for these use-cases, it'll be our go to, and has been for the past 4 years since we moved our Gaming community off Discord and family off other chat apps. Hosting a server is super easy now, and in just a year it's night and day compared to just a year ago as they nail in the spec for Matrix 2.0 - https://github.com/element-hq/ess-helm We federate with other Matrix servers and communities.

Signal is too centralised. Meanwhile, my private comms server was up, I was able to hop on a call with my crew and play, and then video-call my family.

Too centralised. Little control. No transparency. No thanks.

Finally migrated my infrastructure to a new connection manager. Highly, highly recommend xpipe.io. In a couple clicks it can trace your infrastructure a bare-metal host, virtualised environment with VMs and LXCs, down to the docker or kubernetes containers. Along with syncing everything encrypted to my private gitea repo, this is a killer solution as far as connection managers go!