Hi, I work with the latest Android Studio, using libraries that improve user experience and speed up the app alongside native ways of doing things.
I checked your link and, if I'm not mistaken, that you need an application that you're going to ship to your customers so that they can see their photos.
If you need it configurable, I would suggest that during the first start of the app, it asks the user to scan a given QR code which contains the URL of the gallery, so that the user doesn't have to input the URL address by hand, and thus ruining their experience. If need be, there should be a Settings button somewhere, where they can change the URL by scanning another QR.
If you like the idea, feel free to contact me so we could further discuss development and use-cases of this app.