Is there anything needed in the dockerfile (e.g. apt install and/or configure anything) to get the GUI?
I tested this on the official debian image, got this error
docker: Error response from daemon: OCI runtime create failed: container_linux.go:345: starting container process caused "exec: \"-v\": executable file not found in $PATH": unknown.
tried xhost +local:$(id -un) on the host too, still the same error.