Currently GNU Modula-2 can be grafted onto a number of GCC branches. The gcc-10 graft is the preferred choice.
git clone http://floppsie.comp.glam.ac.uk/gm2 gm2-floppsie git checkout gm2-10
git clone http://floppsie.comp.glam.ac.uk/gm2 gm2-floppsie git checkout gm2-master
Binaries can be found under the Platforms tab.