@sulcud on second thought, I'm not sure what prevents one from re-signing the ipa file with their own provisioning profile, and reinstalling. See also here which has a lot more info, and a script to do the work for you.
It appears that this allows you to update the entitlements plist, and update code signature to match whatever c libraries you are making.
Presumably this means the "new" app gets a different name, and you then have to sideload it.
It would be super interesting to hear if this works -- it might raise the possibility for people with XCode to integrate their own custom compiled dynamic libraries and call them from pythonista (scipy/pandas?)