It's not officially part of the Pi Hole project, but I've been using https://hub.docker.com/r/diginc/pi-hole/ for about six months on a Raspberry Pi (though they support other platforms) and had no issues. They also​ keep up to date with new releases within a day or two usually.

From Br. Eng. "shut your piehole" (slang), meaning "shut up".

American English as well, though I did miss the joke.

yep, the name does explain itself, but "pi" and the logo are hinting at raspberry pi

It might just be it was initially made for Raspberry pi and then expanded over time

Exactly that!

The name has just kind of stuck, even though you can in fact run it on most linux distros (We officially support Ubuntu/Debian based distros, but there is limited support for Centos, and even forks for Arch, and Docker!), on a whole host of different hardware.

This is the correct answer.