Hi im the author of the offgrid github issue, the issue solution is being disscused on Pre-RFC: Implement dependency retrieval primitive - #4 by RaitoBezarius
i will add that this is not a niche capacity, right now you only have to options, install with an image that has all you need or setup your own nixpkgs server, both options are not convenient neither useful for something as simple as for example install ripgrep, firewall utilities…