Honestly I think all native GUI is in a tough spot right now. The desktop market has matured so there aren't any large companies willing to put a ton of money into new fully featured GUI libraries. What corporate investment we do see into new technologies (Electron, SwiftUI, React Native) is mainly to allow developers to reuse work from other platforms like web and mobile in order to cut costs on desktop development. Without that corporate investment I don't think we'll ever see any new native GUI libraries become as fully featured as Win32 or Qt Widgets.
I 100% agree on pretty much everything. The "webapp masquerading as a native app" is a huge problem, and IMO, at least partially because of a failure of native-language tooling (everything from UI frameworks to build tools --- as the latter greatly affect ease of use of libraries, which, in turn, affects popularity with new developers).
To be honest, I've been (slowly) working towards my own native GUI library, in C. It's a big undertaking, but one saving grace is that --- at least on my part --- I don't need the full featureset of Qt or similar.
My plan for the portability issue is to flip the script --- make it a native library that can compile to the web (using actual DOM/HTML elements there, not canvas/WebGL/WGPU). And on Android/iOS/etc, I can already do native anyway.
Though I should add that a native look is not a goal in my case (quite a few libraries already go for that, go use those! --- and some, like Windows, don't really have a native look), which also means that I don't have to use native widgets on e.g. Android. The main reason for using DOM on the web is to be able to provide for a more "web-like" experience, to get e.g. text selection working properly, as well as IME, easier debuggability, and accessibility (an explicit goal, though not a short-term one --- in part due to a lack of testers). Though it wouldn't be too much of a stretch to allow either canvas or DOM on the web at that point --- by treating the web the same as a native platform in terms of displaying the widgets.
It's more about native performance, low memory use, and easy integration without a scripting engine inbetween --- with a decent API.
I am a bit on the fence between an immediate-mode vs retained-mode API. I'll probably do a semi-hybrid, where it's immediate-y but with a way to explicitly provide "keys" (kind of like Flutter, I think?).