Dabbling with yet another #PKMS: Obsidian (#ObsidianMD) also does the whole note linking + graphs + tags, but at least there's a free desktop client extendable by plugins, and I could do my own free syncing + versioning: https://obsidian.md/
Currently incorporated some notes from previous online courses + using it for ongoing notes for a training program, but will probably try redoing notes for past uni modules + outlining books/articles
On a random note, I found this bottled iced #tea that I guess you pronounce as "Cha Pi" (茶\(\pi\)).
It's sweet red tea with rose + lychee (maybe a little too sweet). I've no idea what \(\pi\)) has got to do with it.