Then you need a First Party uservoice to add that functionality.
Or get a developer to build that out for you, to convert what google generates into “channel segments” or "one off events.
The “primary” calendar for “Twitch” is “Twitch’s Calendar”
What you describe is chanign the primary to “google”
You have the additional problem of the fact that Google Doesn’t have a “what game is streamer gonna play” so all your events would import from Google to Twitch wihtout a category/game attached to it. So it doesn’t make sense for Google to be the “primary” as it will lack a number of data points.