What I would like to have is a small Nextcloud installation (max. 200MB, preferably even smaller) that I can host on a ultra-cheap tiny server. I just need file sync, calendar and contacts. The total size of the synced files isn't much either.

Nextcloud used to be small enough for this, but they kept adding things, bundling word processors and other stuff I don't need, meanwhile making the contacts and calendar optional. I have had to move to a larger server only for this reason, to keep Nextcloud at a supported version.

Does Syncthing have contacts and calendar syncing? Any others? I like having a central server.