I definitely feel this frustration. Unfortunately, I don’t see a good way to bypass this period of fragmentation while protocols are developed. There are a lot of protocols that were a higher priority than these, but they will still receive support. I do think maybe the remote desktop protocol could’ve been a more generic desktop control protocol, which would help with the weird error messages.
It feels like a lot of this is framed as unnecessary security theater, which I wholeheartedly disagree with. Apps should absolutely not by default have the ability to control desktop input. The current lack of support is annoying, but that doesn’t mean it should be implemented insecurely, and a secure implementation takes time. X11 is still supported by Plasma, so if you need these features, that is still an option until they’re fully implemented by your preferred compositor.
Honestly, the fragmentation of the input automation doesn’t look that bad to me. It seems as if the big compositors support the remote desktop protocol, even if the popups are a little unintuitive and gnome doesn’t support saving the permission.

