LED 7" Round Headlights Upgrade!!

What you're saying is basically right.
You may be OK with Vixen.
Here's how it works.
When the car was made the manufacturers used parts that met standards set out in federal regs and industry standards.
Fed regs for safety are Federal Motor Vehicle Safe Standards (FMVSS) which often also reference SAE and other standards.
My understanding is that lamps, marker lenses etc are not sent in for approval. Rather the manufacturers test and mark them to identify what standards they meet. Only if there was a problem would the government do an independent check.

When we drive a personal car on public roads we need to maintain them to the state's standards.
Most (all?) states allow lamps made to newer standards.
If the markings on the lamp are legit (in other words the manufacturer actually can prove it actually meets the standard for using the marking) and the beam pattern is correct, you're probably completely legal.