One other option is to use the Seek app (which is built by iNaturalist). It can ID stuff while completely offline. However, it’s not integrated with iNat, so it won’t upload your photos. So the workflow would be:
- Open Seek app to ID something.
- Take a picture with Seek.
- Open your phone’s camera app to take a “real” picture (at least on my iPhone, photos taken by Seek are low-res and not geotagged).
- When you’re in cellular or wifi range, upload the real photos while reviewing Seek for the IDs.