There are some activities where the program guide is not relevant. For example, I have an AppleTV activity. — Staff replied: “Exactly such a setting already exists. Under the guide settings gear icon, tap the Guide Setup button at the top and then you'll see a list of Activities to enable or disable the guide.”
There are some activities where the program guide is not relevant. For example, I have an AppleTV activity. It would be good to have a switch in the activity setup that automatically hides the program guide when that activity starts.