To be clear, there has been no statement from Niantic that apps that put these coordinates on the photo are considered geo tagged. The location data is imbedded in the photo if you have that feature turned on.
I do not use one of these apps. I could see it could be useful if you want to check for yourself what location info your photo is showing. The only external tool that Niantic has ever recommended is this one, and I have never used this either: Leveling Up Your Appeals and Removal Reports