niri isn't packaged on jammy, and it's not just a missing package — the surrounding stack is too old to run it cleanly. The things I had to fix: libinput < 1.27 has no dwtp config symbol niri expects, so it won't link libwayland 1.20 lacks high-res scroll (axis_value120), which makes Firefox abort under niri with "wl_pointer has no event 9"...