All is KDE minimal.
I followed the X2Go Arch wiki.
Using 2 Virtualbox machines, one as X2Go server and one as X2Go client, it works fine switching to testing branch.
Now I installed physically, the server side, on a mini-itx board, also testing branch.
When connecting I can see the desktop and mouse-cursor on client side.
Clicking the menu or a application does not show up (client side) but it does on server side monitor.
It does not matter if I use the X2Go client in the VM or on the host, switching branches makes no difference either, outcome is the same.
Have been looking around for this but was not able to find a similar post, here or elsewhere.