Whichever is easier for you guys. Personally I prefer separate latitude and longitude parameters.
@George mentioned about the possibility of building a bulk server action in the future, so I imagine built for the Wappler UI.
"https://nominatim.openstreetmap.org/search?q=wappler&format=json
Maybe we can build a server action from so you can do it in batches server side and save the coordinates in database. But you can do it directly with the API action as well."