You can definitely run GUI programs in Docker. almost all of the containers I run have GUIs. Am reading about setting them up and you just change a display value to allow it.
The whole point I'm making is the isolation of Lb. Set it up to work in Docker and it will run on basically any Linux distro. I (and I'm sure many others) will gladly pay for another license to be able to run it on Docker!
I also think it would be great if a docker version was available because you could run a server on your network that hosts Launch Box, emulators and roms. Then have an app for your streaming box that kind of mimics steam link. you can play all your games via Big Box from your living room. Would be a killer solution I think.
For Unraid (Linux based), I go to my Unraid GUI and click the Docker tab, select which Container I want to open, hit open and it's GUI pops up in a new browser tab.