Is there any policy to prevent apps displaying ads in the touch bar?
However, it sounds like in the absence of private framework usage, the only way for your app to show anything in the bar at all is for it to be in the foreground.
So it would seem like less of an issue than even showing ads on the main screen, where any app can technically create windows that float over all the others and can't be moved by the user.
"""There is no need, and no API, for your app to know whether or not there is a Touch Bar available. Whether your app is running on a machine that supports the Touch Bar or not, your app’s onscreen user interface (UI) appears and behaves the same way.
The Touch Bar dims automatically and wakes when the user touches it. Do not show alerts in the Touch Bar, and do not use the Touch Bar for widgets."""
For the touch bar, you aren't doing the actual rendering; the OS is. Only the OS knows if there's a touch bar, so without a kext or something, it seems there's no way for you to know if the touch bar exists.
if(!touchbar) return MAKE_SUCCESS_GREAT_AGAIN;