I used to write Qt in like 2006 but I've given up. I've been rolling my own thing in Rust. GPU first, ECS (https://en.wikipedia.org/wiki/Entity_component_system) based. It's surprisingly pleasant.
I think there's a fundamental complexity that pervades popular ui libs (incl, qt, gtk, etc.), that doesn't need to be there.
However, note that I also use OOP. No inheritance (death to gobject!), but the whole thing is based around interface polymorphism. This actually simplifies the design significantly. And you can implement an imgui on top of it pretty easily, if you really like hidden state.