Have you managed to find an alternative? Your concerns resonate with me but I still don't know the best way to automatically backup all the photos I take on my phone, search them later, etc
Caveat 1: it's technically a sync, not a backup. The risk remains that Apple deletes all my pictures remotely, and this deletion propagates to delete my local copies. There is still a recycle bin, but perhaps Apple has some way of deleting even that remotely. I don't think so, but it's a risk. To mitigate this, I periodically download all pictures to "cold" storage. It's fragmented and poorly categorised but at least the pictures are there in the case of a catastrophe.
Caveat 2: this only works in the Apple ecosystem.
For Unraid/Windows (Docker), I found this: https://www.reddit.com/r/selfhosted/comments/tsxi5k/icloudpd...