On the 2000 Impala I used to have, I bought some of the aftermarket headlights and their beam pattern was not as good as the aftermarket lights that were in there when I got the car. The OEM lights in the 2005 Impala that replaced it were much better in that respect, even though they needed cleaning.
I found several YouTube videos, of which there were two in particular I liked. One was to sand the plastic with 600 grit paper and then spray them with a uv-resistant clear paint (available at WalMart and such, as it turns out). The other video was of a guy that did internal mods to the headlights, with additional leds and such. He took new OEM lights, put them in a kiln at 170 degrees F for about 8 minutes. That softened the urethane sealer that held the two light halves together. It was gooey enough to separate the halves and do what he did. THEN, he told where to buy new sealer to put it all back together again. I thought of the many '78 Cordobas that needed that sealer after several summers in TX, without needing the kiln for the tail light lenses to separate from the reflector.
Seeing that, I got the idea to buy the aftermarket lights to use their new lenses on the existing reflectors. Then to get the approved urethane to put it all back together again. Best of both worlds, it seemed to me. OEM beam pattern with new clear lenses. Never did get t, o do that, still incrementally sanding/polishing the ones I have.
Once you do get things sanded and polished to where everything is clear, non-painted, you will need to polish them every so often to keep them clear. Possibly some of the newer hybrid ceramic "wax" can make the clearness last longer? Which makes the clear paint option seem more appealing.
I got one of the Meguiar's HD kits, but mine needed more work than the two grits of abrasive supplied could handle. But it was a start, at least.
Watch the YouTube videos and see what you think.
Of course, you can always upgrade to lights with projector beams and such, too.
See what you think,
CBODY67