Re: Bangalore should have innate digital threat inside her smoke.
One idea was to temporarily reduce movement speed after using smoke, but I'm not sure how well that would feel when playing Bangalore.
Another thought was If you hit an enemy with the smoke canisters when it explodes it tags them making them identifiable as if you had the Digital Threat optic. This way you have to accurately hit the player with the smoke in order to get the extra ability. There could be an identifying powdered in the smoke grenade that is left on nearby players, allowing Bangalore to see them through the smoke.
Her glasses are able to detect the identifying powdered or residue. If you were to smoke the same player(s) again that were tagged you would be able to see them again because they still have the powder on them. This would also hold true if they were tagged early in-game and then ran through smoke late game. (if that is too OP then you could say each Bangalore has their own unique identifiable powered in their grenades, but that could be a neat experience when the late game as a Bangalore you happen to see another player tagged in smoke from earlier on and from the other perspective if you get tagged you need to remember not to run through the smoke!)