ZorinOS is basically a set of GNOME extensions and packages, to make it look traditional. It is very stable as far as I know and also has lots of GUI customizations.
As people might prefer a traditional Desktop, I think modifying GNOME makes way more sense than what Mate, Cinnamon etc. do. It has Wayland support effordless for example.
Zorins installer is a total mess and would highly benefit from Fedoras surrounding infra.
ZorinOS looks just like I would expect a hacky GNOME to be. The theming is opinionated, but I think the panel and appmenu are neat and would be useful projects.
Interesting, I thought Debian = LTS using GNOME 43. But RHEL is even more stable here. I assumed there were official versions. Have not checked which version they currently use
Debian does tend to pick LTS / ESR releases of software when available - e.g. Firefox. But no, GNOME does not do LTS releases though in practice if you pick a version that ships with an LTS distro I guess you can at least get critical bugfixes from their VCS, even if those at some point stop making their way back upstream.
Note that Debian has a separate LTS effort - Debian -- Debian Long Term Support - but this is not handled by the normal security team. And unlike RHEL / Ubuntu Debian does not really have predictable release cycles