I wish I was still able to access my old repository at work now. We did a ton of information gathering, not limited to motorcyclists, from the past 30+ years from multiple countries.
As
@m in sc says, the shape and distance of the lights will help a human brain determine distance and speed (i.e. helmet + headlight lights vs. two headlights very close together that could be perceived as one). Changing or irregular movement lights (such as ankle straps on a bicyclist, or reflectors rotating on bicycle wheels) will help someone see you more than static reflection or lighting equipment.
Ultimately all of this does require the other driver to be paying attention and/or not be a total a**hole to everyone else, and I hate to say it but that sh*t is in short supply. My ex-wife is legally blind at night and is still allowed to drive. She had "I can't see where the road is anymore and blew a tire by driving off the roadway" bad night time vision.
I have stories. THAT is the kind of driver that is sharing the road with you, completely legally, and I'm sorry to say that no amount of lighting, reflectiveness, or high viz clothing will ever save you from such a driver. The only way to win is not to play the game.
If we're talking about daytime riding though, I do actually have a suggestion. Be weird. Like... SUPER WEIRD.
I did once do a 100 mi charity ride wearing a chicken suit on a fixed gear bicycle as a gimmick to fundraise for cancer, and there are photos and even video footage somewhere, and I tell ya... pouring rain, terrible lighting conditions, yet EVERYONE saw the chicken that day. I have never had as safe a ride as I did while wearing a giant fluffy chicken suit. Everyone gave me a wide berth. And I can imagine if someone had hit me, they would have been all, "How the f**k did you not see a 6 ft tall chicken?"
IMO helmet covers count as safety equipment.