I fear GNOME doesn’t have support for running with other compositors, but I could be wrong, couldn’t find anything about it online.

From what I’ve searched, a good alternative is PaperWM, a GNOME shell extension that provides tiling and scrolling features similar to Niri.

…you may also be interested in trying Niri with Noctalia Shell, though I don’t know if it’s easy to setup, or how similar it is to GNOME’s UI, since I just use Waybar.