It's particularly frustrating because of how trivial the solution appears to be. Trust on first use is more than sufficient in this case, so asymmetric cryptography with a randomized key would be fine. I realize mass produced electronics can be very cost sensitive and that a PKI chip might add a whole $0.70 to your product (https://www.digikey.com/en/product-highlight/a/atmel/atsha20...), but still. I paid ~$50 for my keyboard! I would not have begrudged the manufacturer an extra dollar or two in order to ensure my system's security.