I agree this is the best, as long as you’re not in danger of running out of battery life.
Have you tried iNaturalist Next? If so, what you can do is import the photos and group them in a batch. The first photo you tap on will be the “first” photo in the observation and it’s used for the observation’s date, time, and location. Then you can drag and drop photos in the order you want when you edit the observation.