Shout out to https://github.com/StefanSalewski/gintro which was super simple to build a simple GUI tool. With Rust I have no idea what to use after trying 5 different libraries.
The downside of Nim seems to be highly unpredictable performance in my experience. With Rust it's much easier to control. This might be a deal-breaker unless I can find some solution to it. Maybe it's just using it more than two weeks and learning the ropes.