In 2020, I started working on a (C++) game engine. Since the only decent open-source UI option was Dear ImGui (which was obviously a bad choice for consumer-facing UIs), I ended up rolling my own retained-mode UI library on top of SDL. Now, it's fully-featured enough that I rarely have to touch it. There's even a major company using it for embedded products.
I don't get why every language's community doesn't just do the same thing: roll an idiomatic UI lib on top of SDL. It was tough, but I was able to do it as a single person (who was also building an entire game engine at the same time) over the course of a couple years.
SDL is not perfect, e.g. you can't get pinch/zoom events on MacOS. IMO, using the OS APIs yourself is better.
In addition, RAII has it's own complexities that need to be dealt with now, i.e. move semantics, which obviously C does not have nor will it likely ever.