Hi everyone,
From the day that I got my RAV4 Prime, I hated the loud alert sound it made when driving at low speed. Thanks to the information provided in this thread, I was able to build a harness that replaces the low-speed speaker with a simple resistor and plugs into the factory harness and allows normal functionality of the car without any error messages. I figured that there might be some people on this forum who don't have the ability to pin a connector or solder wires who might be interested in buying a plug-and-play harness, so I made a few extra since I had to buy multiple resistors. This will work on the Prime as well as the hybrid (as well as the 2021 Venza).

Disclaimer - using this harness may cause your car to be in noncompliance with state and federal laws, you should not have it installed while driving on public roads as it may expose you to extra liability should a collision occur.