Regarding photos, and videos specifically:

I know you said you are starting with selfhosting so your question was focusing on that, but I would like to also share my experience with [ente] (ente.io) which has been working beautifully for my family, partner and myself. They are truly end to end encrypted, with the source code available on github.

They have reasonable prices. If you feel adventurous you can actually also host it yourself. They have advanced search features and face recognition which all run on device (since they can’t access your data) and it works very well. They have great sharing and collaborating features and don’t lock features behind accounts so you can actually gather memories from people on your quota by just sharing a link. You can also have a shared family plan.