I’d recommend Flutter Desktop if you/your team are already comfortable with React development. Even if you don’t know Dart, it’s easy to pick up, has mature tooling, and Flutter’s UI API is very similar to React and will be comfortable for a lot of devs very quickly.

It also leaves open the possibility of eventually supporting your app on web (with, say, a backend or even WASM doing the FFMPEG stuff). Few desktop UI lots offer this.