Raspbian desktop is not a problem, just a waste of resources.
Libreelec is not debian based so those instructions obviously won’t work. Libreelec does support docker though, but there are some problems getting it going, search this forum and you’ll see.
I think OSMC might be debian based, but I haven’t used it in ages, and haven’t tried the specific (or any) ha install method on it. Worth a try I suppose. Let us know and be sure to document it if it works.