I use OneDrive for the auto-upload feature. I know it’s not selfhosted, but I want an off-site copy of my pictures anyway, and the phone app works really well for auto-uploading. I had previously tried Nextcloud’s auto-upload, but many times the uploading was stuck and I had to fix it manually.
I then have nightly rclone jobs to download the photos from OneDrive and store them locally. To view them locally, I use Photoview, which works really well with an existing directory structure.
Same. I’ve installed a few apps to keep an eye on their development, but web is still my favourite for now. Some of the apps have gestures and easily collapsible threads, but UIs aren’t completely polished yet.