The product categories are shown in another menu items section called Product Categories.
You need to enable it first in order to use it.
To enable it, you must click the Screen Options button on the top right side of the Appearance → Menus page and check the box for Product Categories.
Link to image: https://snipboard.io/N6spq3.jpg
Once you’ve done so, refresh the page and you should be able to see another menu item selection for Product Categories.