It’s a specific “Window” of the extension, which provides other Roon-related stuff, which I do not use. It’s very neat, gathers the graphics and all, even the disc is spinning.
It’s pretty straightforward to get going, no speed bump that I remember, just follow the instructions.
Now, rolling out Kodi just for that is a bit like using a sledgehammer when a spoon would have been enough…
Kodi on a Raspberry Pi is dead easy and quick with LibreELEC.