When I get to a computer, I'll confirm if the #+CAPTION: and/or #+NAME: is needed for the inline images to show. Above works fine for exports, so I assumed that the inline images should show fine too.
Following up on that, the inline images work just fine with.
# ()convertfrompdf:t
[[./foo.png]]
One can add
#+STARTUP: inlineimages
if the inline images are not always set to be shown by default.