I can’t compare it to pigallery, but imo it really isn’t fully usable. Lots of bugs for me. I’m still running it but waiting for it to be ready to replace Google photos. It has transcoding errors in the logs and file tracking issues (extra files). All of my recent motion photos are not detected. And I have read on GitHub that they are still working on fleshing out automated repair tasks.

As someone that’s never used any of those services, what’s the difference between this and bypass paywalls clean?

If you create an LXC, then go to Resources --> Add --> Mount point, then you can basically just mount the proxmox drives / folder as a folder within the LXC environment.