What photo scanner technology to use in the mobile app?

Question

Android

Good afternoon!
We are currently looking for a technology (some kind of ready-made solution) of a photo scanner for scanning A4 sheets of paper from a mobile application.
The mobile app is yours. I just want to build scanner technology into it.
Of the criteria - both free and paid solutions are suitable. Application in iOS and Android versions (accordingly, the solution must be embedded in both iOS and Android versions). There is only one requirement for the technology itself - to recognize A4 sheets as best as possible and turn it into the most real, readable scan possible (high quality of the photo scanner itself).
What can you advise?