AFAIK the vest in cars thing is French, but that has become irrelevant.
The yellow vest (gilet jaune) has become a symbol of resistance against the all-powerful state, and those attempting to control the entire dialogue.
Some here have suggested a US version with Blaze Orange Hunting vests.
I’d disagree with that, as it conflates gun control with other complaints against the gov’t.
Anything bright helps the Gov’t target individuals in the streets.
I’d suggest going with a camo vest/jacket with a minor blaze of orange strip somewhere in a less critical body zone.
I was in an old school family run camping store about an hour ago. They have a lot of clunky outdoor stuff, more survivalist/hunter than Sierra Club. They also sold yellow safety vests. I remarked that they had them, and the woman running the place said “do you want one?” I said “No, but they’re very popular in France right now. Everyone’s wearing them.”
She laughed.