I dug through it a tiny bit because I was curious as well. To me it looks like OS-specifics aren't dealt with in the project. It uses bun to run the TypeScript. From the getting started docs the project just opens a browser window for the UI. I didn't look to see if this meant the user's default browser or a bundled browser.

Native bindings written in c/objc and a zig binary that bun spawns.