I have used obsidian and excallidraw for my note taking, especially excallidraw for math where I draw with my tablet. But since I started using emacs for programing I would like to move to org roam for school notes. However, I have not found a good alternative program for obsidians excallidraw plugin (I find gimp a bit to big for my purposes).
http://www.styluslabs.com/
Maybe try Write?
This is what I used for math lectures.
This app can be configured to produce plain SVGs which can theoretically be embedded into org-mode documents and can easily be stored in git. I have always used it stand-alone though.
It’s proprietary and the UI looks like an Android app from 10 years ago but it’s the best hand-drawing experience I’ve found on Linux.