Right now you need to either set udev externally or use sudo for openocd. I want to set this automatically or do some magic with the user so that openocd can be used direction when using nix develop.
The lines in configuration.nix are:
users.extraGroups.plugdev = { };
users.extraUsers.conectado.extraGroups = [];
services.udev.packages = [ pkgs.openocd ];