How to add a toggle button to the Game View tab?

Hello!
I want to add a toggle button to the bar in the Game View. How to do that?
I want my button to be beside the [Maximize On Play], [Mute Audio], [Stats] with the toggle functionality.

 

AFAIK there's no built-in supported way, like with a [MenuItem] attribute with a wonky tag, but here's the source: https://github.com/Unity-Technologies/UnityCsReference/blob/master/Editor/Mono/GameView/GameView.cs

Dig around and see if there's anything you can inject into via reflection.