Just now realizing that I run:
sudo nixos-rebuild switch --flake ~/.nix-config/#
Running as sudo isn’t going to use the ~/.ssh/ config, but instead /root/.ssh. I put my key in /root/.ssh and this is fixed, but I guess I should ask: what’s the recommended approach for downloading private repos during a nixos-rebuild? Should nixos-rebuild run as sudo?
NixOS manual doesn’t mention running sudo when using nixos-install or nixes-rebuild… Hmm.