This seems quite offtopic for this community. If you want to selfhost your own Lemmy server though, people here may help you

Matrix, and I recommend selfhosting Continuwuity as it is lightweight and easy to spin up. Your other option could be XMPP with Snikket or proper Prosody.

Though do you have any particular features you wanna bring over from Facebook Messenger?

Pihole would be easy for a RPi 4. I’d also consider AdGuard Home which does the same thing, but has out-of-the-box support for encrypted upstream resolvers. I eventually moved on to Technitium for more advanced use cases (hosting my own domains, native config syncing between nodes), albeit it can use a bit more RAM.

Hi, as someone running their Matrix server on the same ware (using Continuwuity)I have some thoughts:

• The bulk of the load is in federation with other homeservers. If you only run it in non-federated mode the resource usage would be minimal like a simple REST API server.
  • If you do enable federation on such a low powered device, consider performance tuning it. DNS tuning is the most essential one, and then you should allow it to use some more RAM than normal (increasing cache capacity)
  • Also if you enable federation, expect it to be the software with the most resource impact. I think usually Jellyfin and Navidrome only uses CPU when you’re streaming something, but Matrix may do a lot more background work because federation and so on.
• Calls are handled by a separate LiveKit SFU, which uses WebRTC for most of its operations rather than HTTPS. So you cannot expose it using Cloudflare Tunnels, and you may run into issues forwarding/routing a large number of UDP ports as well.
  • I usually recommend renting a VPS for Livekit instead for simpler config and networking. But if you somehow get it working on the Pi itself as well it’d be great to know.
• I used mautrix-whatsapp a long time ago for the bridge. It was good enough, but do note that it is just a stopgap solution to prevent social isolation. Its better to eventually move people to free protocols.

I’d also like to rehash what the other commenter say in that you’d get much more juice out of a mini PC or some other non-embedded devices. This is for all your software anyhow.

And yes, Continuwuity can run in docker compose. There’s a few example files for it on the site, feel free to check it out and ask in the support room.