Tino,
Thank you. That is enough to get me on my way.
One last thought. My use case involves the external app generating a series of numbers and letters which then need to make their way into a text box in the survey. Right now users have to switch apps, write down with pen and paper the letters and numbers, and then switch back to kobocollect to type them in. One solution would be to integrate the external app, which as discussed, is a bit of a hacky enterprise. Another option would be to remove the need to write down the code and allow users to copy paste between the apps.
Now, because the FormEntryActivity class overrides the contextual menu, it is not actually possible to paste into kobocollect. In principle it seems like a useful feature to add. Would you be open to including a paste item in the contextual menu? I could try working up a pull request if you would find that useful.
Best,
Ian