If you are using #NixOS with discreete nvidia GPU and don't need it, consider explicitly disabling it. Even if it doesn't appear in system dialogs by default it keeps drawing power. Disabling it reduced power consumption by half and also solved some issues regarding electron apps startup.
The configuration to disable is here: https://github.com/NixOS/nixos-hardware/blob/master/common/gpu/nvidia/disable.nix