Nostr offers that. Run your own relay, connect those with whom you want to share to that relay and post to it.
Discussion
yes, I get that and it's awesome in theory. but for the average user, running their own relay or managing access isn't practical. we need simpler tools built on top of that flexibility
It really isn't that hard with umbrel: download the relay app, set up tailscale for remote uninterrupted access, add the devices to the tailnet and you're good to go. Total control and privacy vs someone else hosting all that for you.