Can the cap on the wheel be purchased?

Just posted the same issue lol.

Might be a rim protector. https://ebay.us/m/aS1ico

Usually can, but not directly from online store. I would contact the Service center and ask a quote.

What version and year?

If I got the right one it’s a whole kit, you can’t just get one piece and it’s $155. 1344274-00-B

Flat tire?

That's interesting. Anything in particular that might've caused this?

For the life of me, I cannot figure out how to remove the center cap.

I had similar issue and just grabbed a single one off eBay. Otherwise is an entire kit for almost $200

You can order parts on EPC.Tesla.com, it is their official parts category, it looks like you would have to buy one wheels worth of them for $155. Sometimes service centers will allow you to order through them and do parts pickup, I have done that before and usually just say “requesting x part for z repair” 20 INCH WISHBONE AERO INSERT KIT 1344274-00-B https://epc.tesla.com/en-US/catalogs/8d917dc8-c246-44ab-9a0b-069127b4262c/categories/3bdbf048-25a1-4ab8-9487-d2b8f49c58a2/subcategories/1bcabd89-efeb-469d-8c20-cf5cec0a6157/systemGroups/94e7f42b-83e0-4d1e-8dff-55021466271f

I put in a mobile service order and they replaced mine free of charge

Bro, put some air in this tires.

Epc.tesla.com

Grab two of the “prongs” and pull hard.

I always feel like I’m going to break something

Id check facebook marketplace first

551$