This problem has been solved in the DEs for quite some time now, global hotkeys is probably the very last thing you want to reach for, when all other options are exhausted.
And when that happens, I don't know about other DEs, but the way you're describing with extensions is mostly how GNOME Wayland already works. If you want to intercept a key, you ship an extension for that, and display a UI to rebind the keys, or you can place additional entries in the system's keyboard settings panel. What you can't do is have random unprivileged processes intercept keys without the user's permission.
This problem has been solved in the DEs for quite some time now, global hotkeys is probably the very last thing you want to reach for, when all other options are exhausted.
And when that happens, I don't know about other DEs, but the way you're describing with extensions is mostly how GNOME Wayland already works. If you want to intercept a key, you ship an extension for that, and display a UI to rebind the keys, or you can place additional entries in the system's keyboard settings panel. What you can't do is have random unprivileged processes intercept keys without the user's permission.