The only logical way to go about this for Sony is to include motion tracking (probably cameras) in a splitable DS5 controller. It would give every PS5 owner everything needed to use VR out of the box if they have a VR headset. As for headset tracking they just need a port for the camera on PS5 for it to work, which shouldn't be that big of a problem. A PSVR2 could then ignore the camera and have it's own camera based tracking solution.
A splittable DS5 as motion controllers would be a nightmare of ergonomics. I literally don't see how that could possibly work in any way.