By and large yes. However, even on NixOS there can be various leftovers in the form of state files in /var and configuration files in /etc (outside the majority

By and large yes. However, even on NixOS there can be various leftovers in the form of state files in /var and configuration files in /etc (outside the majority, which are managed through Nix). Unless you nuke most of the root filesystem on every boot [1]. [1] https://grahamc.com/blog/erase-your-darlings https://grahamc.com/blog/erase-your-darlings