I use Obsidian[1] pointing at a local directory of markdown files which is also synced across my devices via Syncthing[2]. Works flawlessly across my various Android/Fedora/Windows/etc devices. Cost: $0.0/year.

I don't really use any Obsidian plugins. Obsidian has good builtin navigation, search, and markdown processing (e.g. LaTeX, code syntax highlighting). It's just as easy as opening a new file in $EDITOR, except its a markdown renderer & synced across all my devices.

There are also a lot of bells and whistles like graph viz, export to website, etc. that haven't gotten in my way.

[1] - https://obsidian.md/

[2] - https://syncthing.net/