This is the only thing keeping me from uploading photos to Drive. I'm not going to explain, but my workflow of backing up my photos from my phone to an external hard drive depends on being able to delete photos on my phone from within Proton Drive.

Ente photos allows you to do this. When deleting a photo from within the Ente app, it asks if you want to also delete it locally. Please make this an option in Proton!

Agreed. Also having the option to toggle off for those who don't want it deleted locally.

Absolutely need this so I don't have to delete unwanted photos both on device and on cloud. Allow this behavior on the mobile app where the offline copy of the photo is, and allow a toggle for those who don't want this feature.

I couldn't disagree more. I hate this in Google. BUT if it is implemented, please add an option to toggle this feature in the settings.

This should be implemented. For those that have a lot of photos, once the photos get uploaded, having the option to delete them from the device itself would be ideal.

This.

should work both ways (synchronize)