Hi,
in that dropdown, only Custom Post Type will appear. So if you want anything else there, you’ll need other CPTs.
Categories can be shown via Advance Search Filters.
Here you have an example with search by distance: https://wpgeodirectory.com/docs/advanced-search-filters-addon-search-by-distance/
Doing the same for category is pretty simple. Go to GeoDirectory >> practitioner settings, open the category field to see it’s settings (in the right side of the screen), scroll down to the last settings and enable use as filter.
Now go to the advance search tab and enalbe category as a filter. You will see a customize my search button now next to your search form and when clicked, the category select will appear.
let us know how you went.
Thanks