I use TiddlyWiki via TiddlyPWA. It’s an offline-capable PWA with builtin sync and encryption. It doesn’t have folders but it does have nestable tags. I don’t think it supports markdown out of the box, but I’m positive you can find a plugin to use markdown. Plugins are crazy easy to install in TiddlyWiki; you just drag and drop the plugin into your wiki window and confirm the installation.

TiddlyWiki via TiddlyPWA is what I use. I don’t know if it supports the S Pen and the notes are all saved in a single HTML file.

If Mozilla open sourced it years ago like they promised, it could be picked up by someone else.

I should have checked the issue tracker before posting this. There’s already an issue related to community discovery at https://github.com/LemmyNet/lemmy/issues/2951

Users can block those with extensions so the data isn’t as reliable