Have you considered using Obsidian paired with Syncthing?

I keep my Obsidian notebook in Syncthing folders and find it works well enough across Windows and Android devices. The plugins transfer too. You would only have to trust the authors when setting up Obsidian for the first time after pointing to the right directory.

You will have conflicts with certain files if you open Obsidian on multiple devices at the same time. The note.md files should be preserved, which I think is what is really needed.