Create PDF From Mobile

Hi everybody,
I've premium licenses for Android-iOS-Windows 10 I would like to achive the following goals:
- Merge PDF: inside the same page or automatically add pages
- Add Images

Can you provide crossplatform API? I cannot find the API for Windows.

For merge pdf:

• Android: PDFTestAct.concat_pdf and NewPage in RDPDFReader module
• iOS: You can use the same Android procedures, using iOS APIs
• Windows: How to merge two PDFs? (Windows)

For add images:

• Android: How to add an image to a pdf? (Android)
• iOS: How to add an image to a pdf? (iOS)
• Windows: How to create an image page? (Windows)