iirc Neon started by Kubuntu developers as a way to install the latest Plasma on top of current Ubuntu release. And if this is the case then it’s not really started as a distro the way Linux Mint or Bodhi Linux mesnt to be.
But as time progress, if Neon started contributing fixes to upstream in this case Ubuntu, and as well as implemeting changes such as using deb version of Firefox instead of Snap then Neon project is so much more than just an effort to package the latest KDE for Ubuntu, hence a distro terms suits them better in my opinion.
Regarding Plasma 6. I tried Neon live session and was surprised by the smoothness that made possible probably because of the Wayland transition, animation feels smooth and laptop fan did not even kicked in, but what i really like so far is the window scaling, i can set it to 125% or 150% and it does not seems like a hack. About the instability issues, its probably that i did not play with the live session long enough but my session is without a crash.
I think google need firefox exist to avoid anti trust, and Mozilla need google to keep the the six figures payroll for the CEO. So yes.