with directional antennas or telescope mounts, it would seem one could do positioning with catalogs of radio pulsars or optical pulsars (with clear skies or above the clouds), by more old-fashioned navigation like once used at sea.

To find your place on the globe you need to know the current time, and the azimuth and elevation of a feature in the astronomical sky.

Since the pulsars have different periods, observing them should allow you to reconstruct the time, and the directions of these emissions then allow you to determing where on the globe you are for such a time.