I just created an issue (https://github.com/actions/virtual-environments/issues/1579) to request Nix support from within GitHub Actions VMs. Please go show it some love if you have GitHub s to spare!
This is something I personally need but I also suspect that this is a promising approach for expanding Nix’s impact and reaching more users. If Nix can become the “go to” method for installing X package in someone’s CI workflow they’ll come to discover Nix automatically. People are also going to be far more willing to try out some new package manager in CI before they install it on their personal machines.