How do you use x2go with this problem?
I know this is not going to be a satisfactory answer...
I struggled with this for months trying to figure out what permissions needed to be configured for the Snaps apps to work in x2go with no luck. It seems to be related to access to /run.
For me it was the final straw for Snap and Ubuntu more broadly. I rotated over to Debian stable (well, Spiral actually) for everything and if I need an application-level jail I use Flatpak. In only a handful of cases have I had to use Flatseal to adjust permissions for x2go compat. Much better experience.
Like I said, probably not a satisfactory answers but sometimes just knowing that there is an escape hatch available is useful.
Now if I could figure out a work-around for when an app doesn't support Xinput2....