I think this is related to the problem that I also have, to be able to read files at compile time.
if there is a function like get_files(path) and get_file(path) in zola, you can check if atom.xml actually exists or not. and then render accordingly.
I’m not good enough with rust to confidently do this, but I looked at the source code of zola and looked how resize_image function is defined and it seems pretty simple to add these functions into zola.