Probably no big external dependencies or any assets. It looks like something full of handwritten code, down to the self-rendered UI-elements. Also it's written in C/C++ and assembler, so there is no unnecessary bloat shipped out-of-the-box.

Because they're good

And it's good. It also seems to have the most flexible plugin system of any DAW that has decent level of usage.

can just swap electron for tauri for example