Yeah exactly the same situation for me. Also when using hyprland.
There is https://github.com/FlafyDev/combined-manager which (from my reading) does this for flakes, but it has some limitations that are currently dealbreakers for me.
There is a thread on this forum about it Combined Manager: New structure for personal NixOS configs - #4 by don.dfh
I am still wondering if there is a simpler solution to this question so that I don’t have configuration lines distributed over multiple files that are not logically connected.