pop! shares dna with elementary (same people worked on both) and probably is closer to that definition. E.g. backed by a company with actual customer support. Different aesthetics though.
Pop's desktop environment looks like a barely customized Gnome3 session to me. I'm not sure I would even call it a fork. Looks more like just a theme.
Pantheon (Elementary) is more of a fork of Gnome3, reusing some low level parts but presenting a much different experience to the user.
They have collaborated with elementary in a few areas though. Instead of gnome software, they have Pop Shop, which I believe is a fork of the elementary app center.
They also use their own installer, which I believe was a collaboration with elementary os.
While I have sympathies for System76 and Debian, there is no way I am going to install an OS with this name.
- How am I supposed to pronounce this? pop? popos? pop-OS? What should I do with the special characters?
- What happens if I accidentally paste this into the shell?
- What associations should the name "Pop!_OS" have? Appart from the english "pop open" something, in German there is: "Popo" -> Childs word for "bum", "poppen" -> "to hump". Both not exactly favorable.
Also, who comes up with names like this? Have you talked to any marketing person to this before deciding on a name. If you want professionals to put this on their machines, better make sure it sounds vaguely like something you might be able to put trust into.