Looking quickly at the prerequisites, while we have most and some we don't have should be trivial to port, there are a couple I don't know and others like libmtp (to download files from the phone over USB) that might be a challenge. Then there's libfii which likely means manually calling our API manually from Python, eg using DosRead() by pushing the arguments correctly on the stack, calling the right memory location and manually dealing with the returned file read kind of thing. Probably need someone who really knows the underlying basics of OS/2 and with time to do tedious programming but that is just a guess.
Then if there are bugs in our Python, they might need fixing.
Might be easier to build a partially functioning Calibre. Still need someone who knows Python as well as porting.