Apple Watch Series 2 got run over by a car - back sensor shattered

Watch functions perfects but the back sensor/charger got crushed. Holding it together with clear tape for now.

How do I fix it? I’ve seen sensors for sale on eBay but I don’t know if they’re knock-offs and how do I attach it? Apple wanted to charge me $299 to fix it which basically meant throwing it out and giving me another watch. Another case of don’t repair just add to the landfill. Sad!