I\'ve been reading more or less every StackOverflow question about Google Photos, and still I haven\'t figured out the answer.
I need, for my Rails app, to get the url o
Refer to the accepted answer.
There is currently no other/similar/better API (by Google) that interacts with Google Photos like Picasa Web Albums Data API does.
Other than the alternatives you've already mentioned, unfortunately, I don't think there's an API out there that has the functions that is (even remotely) similar to what you're looking for.
With all that said, questions asking for software libraries or tutorials and whatnot are considered off-topic here in Stack Overflow.
PS: The request for an official API by a lot of devs is expressed (and hopefully heard by Google) in a lot of sites for quite some time (like this one). Belive me. (sigh) I understand the frustration.