Good for you? I guess.
I do not really like them either but I am not sure what point you are making. Their point is that these images result in more viewers, even accounting for your absence. What are we meant to do with the information that you are out?
You cannot run a GUI in LXC / LXD. If somebody thinks otherwise, please point me in the right direction as I would love this on Proxmox.
Distrobox sounds very close to what you want. You can run the DE and your GUI apps in a container. I think you still need a window server ( Wayland or X11 ) locally though I believe.
You can see your VMs in a web browser ( like Proxmox does ). Again though, the GUI for that has to be hosted in something else.
The other option is to use QEMU and display to SDL. You can do that without a native window server. That is more virtualized than a native window server but now we are starting to add overhead that may not be necessary.
There are some pretty small Wayland compositors and you can start them from the command line. Velox is just a few megs I think. You do not need a graphical login manager. All you need is a compositor and you can run distrobox from there.