Login to Pi via X2GO.
Terminal.app in your X2GO desktop environment.
In Termial.app, request an exclusive node to run X Windows job and check which compute node is granted.
$ salloc -p cpu -N 1 –exclusive; squeue -u
Login to the compute node, say
node300, with X-forwarding enable.
$ ssh -Y node300
Start your GUI app on the compute node, whose GUI should be displayed within your X2GO environment.
When everything completes, log out from X2GO via