Geotagging any photo in LightRoom Classic

Mobile phones can tag every photo with the current GPS location since they already have a GPS built in. My older Nikon DSLR does not have this feature. Which annoys me, all my photos are taken outdoors, I’d really like to get the location stamped into the metadata as a record.
If one had more money than brains, one could purchase a dedicated GPS, slot it into the camera hot shoe where it…