I expect they're getting their displays from the same place Sony, HanLin and iRex are getting theirs, if that's what you mean ....
Ah, now I get what you're saying. I don't think Sony
could buy 'exclusivity' if they wanted to -- we have anti-monopoly laws here in the U.S.

(and I don't mean the board game!)
Besides, the e-Ink corporation has to want as many buyers for the product as they can manage, so they'd certainly be unhappy if PVI started trying to sell monopolies.