If I was going to try using something new it would be Flutter/Dart. If I was going to use something (old) that might be Qt, or something that I know from way back straight up Java Swing. For something big a framework like Eclipse RCP. Should be able to use Kotlin for these now at least.
I don't understand the hype around Flutter for desktop. It's possible to make a cross platform app, but it only looks good for Android and iOS. I haven't used react native, but I imagine it would be better for cross platform apps because you could create a separate UI for mobile and web, but keep the same backend logic for both.
As far as I know, all react native gtk are abandonned so I would not be so sure about that, flutter does better in this area