The final cut of TMC Podcast #34 is available now with topics timestamped. We covered Tesla's rollercoaster prices, Toyota pushing junk science, Mike's new Model 3, Optimizing track mode for snow driving, FSD V11 apparently coming by the end of this week, and more. You can watch and check out the chat replay on YouTube.
There isn't an official one from Tesla (IMHO the tint and small back window make seeing anything in the back impossible) but there is a forum member who developed or is developing their own. Do a search for trunk cover and you'll find a couple threads on it.
A better way to get cargo privacy would be louvers for the rear window. The louvers would not have to be very large to block sight lines to the cargo area. IMO this would be better than a pull-out cover because it would never look like you're trying to cover something.