GCloud App needs FTP - do I need a VM or can I create an FTP app?
App Engine projects are not based on server virtual machines. App Engine is a platform as a service, not infrastructure as a service. Your code is packaged up and served on Google App Engine in a manner that can scale easily. App Engine is not a drop-in replacement for your old school web hosting, its quite a bit different. 
That said, FTP is just a mechanism to move files. If your files just need to be processed by a job, you can look at providing an upload for your users where the files end up residing on Google Cloud Storage and then your cron job reads from that location and does any processing that is needed. What results from that processing might result in further considerations. Don't look at FTP being a requirement, but rather a means to moving files and you'll probably have plenty of options.
I'm running a PHP app on GCloud (Google App Engine). This app will require users to submit files for processing via FTP. A python cron job with process them.
Given that dev to prod is via the GAE deployment, I'm assuming there is no FTP access to the app folder structure.
How would I go about providing simple one-way FTP to my users? Can I deploy a Python project that will be a server? Or do I need to run a VM?
I've done some searching which suggests the VM option, but surely there are other options?