If your referring to the HU...It is not that important...Every important thing it does is redundant...OK - let's pit nicks then.
A most critical element of that legislation (which has been amended several times since originally implemented 44 years ago), includes the clarification that accepting 3rd party services and products applies to warranty service and maintenance (only) - NOT BASE COMPONENTS of a product (like the main navigational Head unit).
Changing your oil or transmission fluids by Jiffy Lube, replacing some light bulbs, or installing some side window shades would be viewed entirely different under warranty support than the most significant electronic core unit of the vehicle. There are also some monetary limits regarding acceptable 3rd party substitutions for warranty repairs in the more current regulatory updates.
This portion is key: "If your aftermarket part somehow causes or contributes to a failure in your vehicle, the dealer may be able to deny your warranty claim—as long as they can prove the connection."
The devils in the details (and regulatory updates since 1975).