"Alternatively it might make sense to build some type of bespoke solution on top of a specific wayland stack, like re implementing what you get of talon in a kde plugin or via sway IPC. This seems viable to me but an incredible amount of work."
I think that is the only way forward. There is no "Linux desktop". There is KDE, Gnome etc. and if you want to do "system utilities" you have to target one of those.
No, that's a terrible idea. The right thing to do is design a Wayland protocol that gives you the access you need, get it accepted into wayland-protocols, and wait for all the compositors to implement it.
Yes, that's a slow, annoying process, but doing something bespoke means either you do the same work over and over for every compositor, or you only support one or two compositors. Neither of those is a good result.
The point though is that there used to be a «Linux desktop» you could target before the Wayland transition. Fragmentation of an already small market segment is unfortunate.