What a stupid, pointless idea.
Of course, I
love it.
Airtac UK has been working on a shotgun tracer, so it's not that outré.
https://www.airtac.me/product-page/shotgun-tracer
Caveat, when I've done hop-up tracer units, they've always been rather disappointing, even when I've bought the most lumeny "UV" LEDs that eBay can provide (for pennies each). I'm not sure what you'd have to do to ensure that you get ones that are
really UV and bright enough to charge up BBs in a fraction of a second.