Continue Sync / Only Upload Unsynced Images / Sync only with Regeneration

We have quite a large photo base and syncing 150,000 images + regeneration takes a long time with some risk of the process being stopped or cancelled for whatever reason.

Would it be possible to add the following functionality:

– More efficient Continue Sync – Right now my browser shows 25,000 images and only way to sync them all is making sure this sync finishes successful otherwise it has to start from scratch again. Would be great if there is a more efficient pause / continue functionality that remembers what was done and what not so you can pause and continue at a later stage without risking having to start over.

– With such a large sync some errors are inevitable. It would be great if you could run only a sync that finds images that have not yet been synced. So you don’t have to manually find images that have not been uploaded due to various errors.

– Sync without regeneration – Regenaration takes a lot of time (for our required sizes about 20 sec) but we have all sizes already on our server. Would it be possible to just upload them to Google without regenerating and update the urls in the database a different way or is regeneration the only way to do it?

Would be happy to donate to improve this functionality.