The bumper cover and the rear diffuser are two separate sections. It is likely that you can put them back together properly if you remove the entire thing. Check out some of the tow hitch installation threads (and videos) to see how to do it. YOU DO NOT HAVE TO REMOVE THE TRUNK LID SEAL. But you do have to remove the rear lights. Be careful not to scratch your paint with the metal torx screw clips (install them AFTER you put the cover back on).
I would not fix this damage with a replacement. I would work on polishing up the minor scratches, replacing the reflector, and remove the cover to assess the damage to the internal flat clips holding the rear diffuser and the bumper cover together and see whether it can be re-assembled properly.
For the bumper cover/diffuser combo, there are approximately 2 Torx, 6 plastic clips (that stuff is in the wheel wells), and 7 or 8 (depends on build date) 10mm head washer bolt combos, holding it onto the car. As above, to access some of the plastic upper clips you need to remove the taillights. One of the bolts underneath requires you to partially remove the rear aero cover to access the head (it is under the aero cover edge).
Holding the two pieces together (only accessible after removal), there are about 8 bolts and a series of numerous flat tabs which latch together.
This is a two-person job. But it really isn’t difficult; people do it themselves for tow hitch installs. Certainly it is possible to break things and scratch things though. Have a moving blanket to rest the cover on. It’ll have a bunch of gravel in it.
To me it looks like the flat clips have become undone, though there may be some damage to bolt holes as well. You can see one of the bolt covers on the rear diffuser has popped open but it might just latch shut again. Or it is all broken. You can certainly get a replacement diffuser bottom section if it has sustained a lot of damage, but I would avoid replacing the painted bumper cover as it will never be as good as the factory paint even at a really great shop. By good I mean adhered to the plastic - Not the quality of the finish which we all know can vary a bit with Tesla! Factory painted covers mentioned above would be nice if they promise not to blend match them to your vehicle! But that’s a lot to pay for minor damage.
Are those 20” with PS4S I see on there? Sounds slippery!
Lucky the damage was so minor, and glad you escaped with your life!
