No clue, but I'd assume this is like any other pro Apple device that will have a bluetooth or some external device SDK and 3rd parties will make controllers for games.
6dof tracked controllers usually need to be tightly integrated with the headset.
Even if they are self tracking (like the Quest Pro controllers and therefore expensive) there's still a bunch of things that need to work smoothly together.
It's not just like making a Bluetooth gamepad.
And one thing we know about expensive, optional peripherals is that lack of developer support is usually it's death knell
Quest-style controllers are something that Apple would have to faciliate. They are tracked using a combination of motion sensors (high resolution but prone to drift) and detection by the headsets cameras (low resolution but doesn't drift) and the Vision Pros raw camera data is only visible to the operating system.
You can connect a traditional controller of course, they showed it working with a Playstation controller in one of the clips, but that's mainly useful for playing traditional flat-screen games on a virtual big screen and not so much for games which actually explore the possibilities of VR and AR.
They'd have to work with hand tracking (low accuracy, no buttons or sticks, no haptics) or a conventional console controller (limited immersion).
Nearly all existing VR games are built around dual controllers and would need significant reworking/compromises to be playable on the Vision Pro.