I just installed nixos with xfce. Being Canadian I selected the GB spelling option and found my keyMap was set to GB. I have a US keyboard. I changed the configuration.nix file and rebuilt but it did not change the layout. I rebuild several times. I still got @ instead of “ until I rebooted. I don’t think that is the expected behaviour for a configuration change. That is my first edit of the config file.
(The categories did not list any appropriate selection. Sorry for the uncategorized.)