Considering an OEM Prius Catalytic converter is $1700 I really doubt the eBay version actually works. The eBay version I saw was $200 but the description says that it isn't legal in California or New York. That is super questionable considering 13 states use CARB emission standards so there are no 48 state legal parts.
https://www.ebay.com/itm/13116948651...4aAhX8EALw_wcB
You would likely need the wiring / connectors too. I'm sure the wire harness got clipped not unplugged.
EDIT: California laws says shops have to install a new catalytic converter not that it has to be OEM.