A friend wanted to change the visor on his Cessna 182 to one that has tinted plastic. He had to fill out a 337 form and use a "certified" (read more costly) visor to be legal.
The ruels for ADSB for experimentals allow non-certified units as long as that satisfy the "performance requirments."
Just another reason to own experimentals as opposed to certified aircraft.
I believe the Passenger Warning sticker on my panel warns that my aircraft" isn't built to the the standards of certified aircraft."
I have also been told that keeping to TSO standards on certified aircraft also helps to maintain pricing.
John M