Yes, FTP is a solution, but that is not what I asked for. The thing is that my kids have a very large collection of pictures. I want to put it all on a website (with restricted access like password protection in nginx, and encrypted partition) to be accessed only by my parents. It’s like a Christmas gift for them, because it’s more than a year since I’ve seen them face to face (pandemic restrictions).
So far I have a storage server from Servarica, and it would fit perfectly. I do not wish to use some Wordpress, and upload files through some plugins. I also do not wish to open FTP ports either. I want to keep it simple: a PHP script to display some images in a hierarchy of directories.
So far, https://files.photo.gallery from @BBTN seems to be the trick.
Again, thank you for all the suggestions so far. All ideas are interesting, and they may help other people too.