How do I configure multiple nixpkgs's instances in flake's

[waffle8946]

The Myth of Stable Unstable

I will add another caveat to this - mixing stable and unstable is pretty much unsupported, so you are even more on your own* than using just one channel exclusively. And of course having multiple nixpkgs instances comes with its own performance and incompatibility problems, especially for GUI apps and “core” dependencies - complaints around glibc or qt version mismatches are common here. One other option for people that want to use stable would be to use a scheme similar to what I use for unst…