Nice! I see that it was inspired by sysz, which I already find very helpful.

Nice explanation =). I am not OP but I am curious about one point: you seem to have the reverse proxy on your homeserver, not on the VPS.

Is wireguard enough then to tunnel HTTPS traffic to your reverse proxy? Or do you need a more sophiscated tunnel (e.g. ngrok, boringproxy).

P.S. I actually assumed that your VPN entry point is a VPS with a public, static IP. Therefore I understood that your were talking about two servers: the home server with the reverse proxy and a VPS as wireguard entry point. Please correct if this is wrong.

mu4e+mbsync+msmtp

The Malazan Book of the Fallen, by Steven Erikson.

I have seen many different ways to achieve that in Emacs. Do you have one to recommend (modes, packages)? Do you synchronise calendars with other devices (e.g. smartphone, server)?

https://github.com/spantaleev/matrix-docker-ansible-deploy makes it easy to deploy.

Not sure about the RAM limitation. If Synapse is too heavy, perhaps a different server (Dendrite?) will be light enough.