@ha-username: “Hass” (hate) is also known in parts of the English-speaking world. One of the first things I did (I’m currently living in Germany) is rename my machine to “has1”, i.e., “Home Assistant Server 1”. 
Back on topic: Thanks @nickrout for bringing up The Last Word again. That at least brings some clarification.
So I want “Home Assistant Supervised” for all my machines and those of the lot of friends I have to support, right? Because it’d give us “the full Home Assistant experience on a regular Linux operating system.” Yay! Exactly what we want! Regular, in our case, being Raspbian Raspberry Pi OS (yet another name change, grr!).
That would bring Supervisor, Add-Ons, an easy experience for the newbie plus all the niceties of a real OS, like installing scripts, using system binaries via commandline sensors and automations, and installing/using, say PicoTTS?
So where to get and how to install that? Because “the Home Assistant Supervised method is here to stay”. And what about “missing for each of the above-listed are the specific details, e.g., the supported operating systems for a Supervised installation or the supported hardware”?