After many years of searching with no luck I happened upon a CD player that actually works in my Model S via USB! It's Automotive Integrated Electronics UBSCDPLAY1 and it's available on Amazon for around $200. Just plug it in and insert a CD--it's that simple. The car recognizes all the tracks as WAV files via USB. You use the touchscreen to select tracks since the player is no frills and only has 1 button--eject. Until this point, I had tried numerous players, portable read/writers, etc and nothing worked. Before you ask...YES I know you can just burn CDs to an external drive and the car will recognize the files. However, I have around 15,000 flac files on a 1TB external drive that takes the car like 10+ minutes or more to index. Now I can just pop a CD in the player without waiting. The interface isn't 100% perfect at times. Every once in a while the CD has to be inserted again or reinserted but this is really a function of Tesla's crappy software interface rather than the player. Also, it does choke sometimes if you decide to skip to another song while in the middle of another. It works best when you just insert a disc and let it play. The link to the player is here:
https://www.amazon.com/dp/B07DHXY5X3?psc=1&ref=ppx_yo2_dt_b_product_details
AIE also makes another version (USBCDPLAY2) which the car will not recognize so don't bother trying that one.
I hope this helps others since it's been a ridiculously long time finding a solution to this nagging problem.