Most of that stuff was very much over engineered in the last two decades.

The backend for my personal notes, tasks, bookmarks, calendar and feeds are files in directories synced with Syncthing across devices.

I ended there after going from one app to another and being tired of all this.

It is self hosted with no server backend (beyond a Syncthing on a NAS or VPS, optional). It is very reliable and works without Internet connection.

I could have put everything in sqlite too and sync it one way or another, but it seemed already too complicated for my requirements.

I can't share it beyond my close relatives but I had the same problem with people using Google or Microsoft before.