I tried setting up HA once on non-docker and it was pretty awful. It has it's own internal dependency management thingy that auto downloads stuff it needs into it's virtual environment.

Much as I love to use standard off the shelf stuff and eliminate original code from my life, my custom automation system has been the one thing I can't find a replacement for, and I don't really expect that to change.

They just don't want it to be repackaged with patches that cause them to receive support requests for issues which are essentially a distro fault

They don't want you forking it for that purpose, either.

https://github.com/NixOS/nixpkgs/pull/126326

Is it technically open source? Yes. Is it spiritually open source? No. Is it arrogance and poor management? Along with many ways this project is run, absolutely yes.

Use it but not modify it? With that attitude it can't even be classified as Open Source.

Hard pass.

Too bad. If they intentionally make it hard for people to make a software follow their distro conventions, be it immutability or reproceability, then they shouldn't be too surprised that forcing the software to behave properly could cause side-effects.