Nextcloud is really not a photo management solution though. The e2e support is nextcloud is really not production quality. Do you use either of these for your setup because I am happy to change my mind.
I use emby these days for managing photos and auto uploads.
You can use nextcloud as the cloud backup and turn off backups within google photos, and then you have a photo manager with encrypted (and self hosted) backups. I have not used nextcloud myself. I use Apple products and pay for icloud. I use Emby as well for media management. What I was getting at is that I don’t want to switch my photo manager and photo workflow when all that the value here is is the fact that the photos are encrypted, there are many solutions to that. Why not sell a hosted end to end encrypted backend that is compatible with google photos and Apple photos?
Ah, I misunderstood what you were saying. So, what you are suggesting is a privacy focused backup option for the existing cloud services. That is indeed an excellent idea. Before I went totally selfhosted, I had a tough time getting my pictures out of Flickr and Picasa web (now both dead!)
I use emby these days for managing photos and auto uploads.