hi, I'm interested in helping to get this package into Debian. I'm maintaining the waybar [0] package, which is a Wayland status bar. In its newest release, one functionality of Waybar also depends on gtk-layer-shell. I started to work on the gtk-layer-shell package in https://salsa.debian.org/bisco-guest/gtk-layer-shell, because I only afterwards saw this ITP. Maybe we can work together on this package or you can use the stuff I already implemented (I haven't found a packaging repo in the mate team for gtk-layer-shell so I figured you might not have started yet).
cheers, Birger (bisco) [0] https://github.com/Alexays/Waybar
