derelektrischemoench's post in Display image via api was marked as the answer
Thx. The critical link I was missing was the whole image- field thing. I read tons of other stuff while googling for a solution and all of them had the echo $page->images - code but only from the code I wondered how PW could find the path to those images.
Of course by storing it in an image field on the site. Quite obvious, actually.