According to the specification you provided:
1. Only a specific url needed to be opened? If yes, only one web view is needed. If no, something else need to be added(e.g. A place to enter url, or buttons to be click and visit other websites you want).
Also, what url to be displayed? If simply a photo, or an advertisement, nothing else need to be added. But If a webpage, a progress bar should be needed to show how many info in the webpage has loaded.
2. Disable a Back button so that not closing app is easy, but do you need any other way(s) to close app? Or just simply open the app and not closing it?
3. Definitely it would be smooth .
All I mentioned above are easy to achieve, but they're all about design and design is important to an app. Certainly decisions are depends on you.
My Background:
Android/iOS Engineer
Augmented Reality Developer
2 years working experience