Well we wouldn't want Proton, it would be 2000x less lightweight than electron! /s
It seems to me that Tauri is maybe a better direction to invest resources in than a direct electron-but-Firefox. Its lighter weight and better sandboxed, and can presumably be configured to run with a Gecko engine instead of a chromium-based webview. I have no idea its status, but geckoview does seem to exist.
I've used Xournal++ and Write, both worked pretty well. Saber also looks promising.
It's going to come down to how the program handles smoothing of the pen input, which is going to differ based on how noisy your tablets data is, and on your handwriting.