Thank you Katya.
We would like to automate this from a script. Is it somehow possible to "pull" the source code from Appery via an API call / FTP / some other method?

How can I publish my app to a custom host of my choice? The documentation has an item like this:

1. Publish to a 3rd party hosting provider of your choice
   But there is no explanation further below or anywhere I could find...