Thanks for the follow up! Apologies that I misunderstood your use case a bit
As far as S3 offline support, it seems more use case specific. On my side, I was able to use offline mode to successfully upload string data, as well as image blob url data from the image component to a s3 file. I triggered the query when offline, and it successfully completed when back online. You could also leverage the variable workaround suggested here: Retool Offline Mode? Does it work for js queries? - #4 by lindakwoo Ultimately, you need a way to upload to S3 without depending on multiple queries
If you need base64 images, on the other hand, that is a bit trickier. If you're using the image upload component, it'll be split it into two queries (which isn't supported offline) to get the base64 data in a JS query and pass it with additionalScope. It's also tricky to loop through multiple images and upload them to S3 since you'd need a JS query to loop over the images.