Check out Codename One which is more like Swing but far more robust. The GUI builder isn't as refined as scene builder but the final product actually works everywhere and far more portable than anything else.
Wondering if Jetbrains will release Kotlin/Native for a set price or charge monthly like most companies are doing these days.
I'm also against "cloud everything" but here they seem to provide an actually useful service.
Notice that this is a compile time feature, you don't need to use it for production.
I build a simple Pacman game. Running on Android wasn't a problem even though the builds took an entire minute to complete.
Compiling and running on iPhone was a nightmare though: At the beginning of the project I was able to run it - some days later I had to tweak the RAM being allocated to the trans/com/whatever-piler - a week later and the weeks after I was unable to compile it at all, there just wasn't enough in my MacBook to throw at the thing.
And the subjective performance was relatively bad too. They tried to reimplement Material Design and it looks somewhat like it, but it performs pretty badly.
Even their own conference app demoing Gluon Mobile is terrible and that says a lot.