Converting GPS coordinates to a (street) address is called reverse geocoding. This is technically quite feasible, and there are a number of websites that will do it, eg https://www.latlong.net/Show-Latitude-Longitude.html. However, this feature is typically not available on (free) mobile apps because (a) it requires a live network connection to (b) a dedicated geo server running the necessary service and geo-database! So you will find that any 3rd-party websites offering an API to perform reverse-geocoding are either a paid service (requiring a token or other authentication mechanism) or if a free service they will impose a strict cap on the number of requests they’ll satisfy from a given client in a given time period. These limitations typically make it infeasible to include such a feature in a free, offline capable mobile app like Collect.
You best bet would probably be to capture a GPS location in your form, and then perform a reverse-geocode to convert this to a (permanent) address field in later processing. And if you have a very large number of submissions to process you may have to consider a paid service (or convert them individually manually using a free website, which will be tedious).