Libhybris not halium, and those are open, the android driver blobs are closed and it's the same on pmOS with halium? They did start open sourcing a lot of their UI components recently, so hopefully this continues, we'll see
It's in a different league as it's a linux phone first and foremost, not degoogled/hardened android, you get full root access as a checkbox in settings that will install terminal app for you to hack to your heart's content, user having root access is not an attack vector for them
The revolutionary part is full linux with root a checkbox in the settings, no need to flash fishy roms, compile graphene yourself etc, it is mostly aimed for linux geeks who like to tinker, if you're fine with android, it's probably not for you (no matter how much they push for it being usable by normal users, there's always fixes/tweaks/workarounds that you'll need to use terminal for, or wait for proper fix, but again full root access is a checkbox in settings that will install terminal for you, for geeks it's the best option out there)