You seem to have some particular privacy concerns that I'm not totally in the know about, but if it being an app isn't a requirement, I've used photojoiner.com with great success and no obnoxious stuff to my knowledge.
They do have an app, but I'm not sure it will meet your privacy requirements.
You sound like someone who has a pretty locked down browser, so all it should get is what you supply, but if you want to keep it locally, I don't imagine this would help you, but if it's not the photos but rather your other data and location you wish to protect, this may work.
Again, I'm not hardcore into data privacy, so I may be off on what you need.