Halium is a hack around crummy vendors doing sub-par work. It is technically impressive but it doesn't resolve the underlying issue that the crummy vendor kernel will never be updated. Saying that Halium is not a good enough solution in the long-term does not make one a purist, it's a simple fact. Devices that rely on Halium are dead-on-arrival.
Except they don't, not really at least. You can't even run a Wayland compositor unless it's hacked up to support Halium, and that's just the tip of the iceberg. It makes sense when you want to run some better userspace on an existing Android device where having a proper hardware support is absolutely hopeless, but in the end it's not that much better than running your stuff in Termux or WSL and you'll find yourself limited as soon as you actually try to do something unorthodox with it.
I'm typing this on a device that doesn't rely on Halium and which actually actually works, without being confined to what distro maintainers happened to manage to hack up or reimplement, so it's not like there are no alternatives.
Devices that rely on Halium actually work. I’ll take that over your perceived “dead on arrival” status right now - especially since by the time anything in that ecosystem changes I’ll be ready to swap devices again anyway.