I remember something that was available a few years ago to reloaders. It was something like a roll of caps that you could pull one off and stick it on the base of a bullet. When you fired the round, that cap like thing created a tracer effect. I never tried any cause it just didn't make sense to me.
I bought some faux tracers like that. Mine are G2 Research Cold Tracers in 9mm. I've only shot one of them in the dark out of a full size SR9 with a 4.14" barrel. After the muzzle flash, I couldn't see if anything illuminated on the way to the target. I'd call the ones I have pretty useless for their intended purpose, but I just base that opinion on one shot.
Only used tracers while in the service for night fire exercises. Only does much good if you are in auto mode so you can guide your shot stream into the target. Used to load every third round with a tracer for that purpose. It is a good exercise in teaching you to keep your head down when shooting at steal targets with fmj pointed bullets - you will see them zingging straight up and sometimes over your own position 😯.
Kind of a novalty item for a simi shooting market place - IMO.