How can I sync my iOS (in my current case, an iPhone8) photos+videos to both iCloud and Google Photos but delete all the photos+videos from my iOS device, primarily to free storage space (on my iPhone)?
Details and (known?) problems
This answer suggests that I can not do this, because deletion of photo/video files from the iOS device also deletes it from iCloud (example scenario below), which violates my goal. However, I'm hoping there's some workaround.
Specifically, I want to "free up space on my device" like I've done several times previously with Google Photos (GP). However, the GP photo/video file deletion may effectively delete the same photo/video file(s) from iCloud--which is what I'm trying to avoid.