How to WhatsApp full resolution photos from iPhone to Android

On Android, I can choose to attach a "document" and then browse the image or video files and select the one I need. On iPhone, it seems to work the same way except that I don't seem to see the full file system of the device, and I cannot browse to the image location. Is there a way, without using a Mac? As a side note, Telegram is happy to allow attaching a file from the Gallery.