Similar to Safari and long-pressing on a photo or GIF, this already brings up the Haptic Touch menu for share options.
The ergonomics of this aren't great on large phones, makes something as common as swiping between posts quite an effort. Plus I find the "dual layer" thing kinda confusing, for instance the Apple News app does this.
This is already an even more common gesture: closing the viewer (similar to the iOS Photos app or video player).
I really don't like when apps introduce a lot of extra modality for common actions, it adds friction and feels like a cop out, especially for something as common an action as this, having to enable it each time would be suboptimal.
In addition to not being very discoverable, this also would require two hands to do which makes it a lot less friendly a gesture.