The Naissant brown conditioner is excellent and on Amazon:
It’s pretty darn strong and MIGHT cover the few grays you have. It will also leave a beautiful brown tint on your brown hair. If it’s too strong, you can always dilute it with white conditioner.
Redken Brownlights is another one and Tressa also makes several great BROWN conditioners. But be careful because many tinted conditioners for brown hair are BLUE and neutralize orangey tones. You don’t want that. The best one here imo is the Naissant.
I’m not a fan of tinted shampoos which are very tricky to use and tend to over deposit tint on the most porous areas (mids/ends) while not depositing any tint on less porous roots. Tinted conditioners spread easily on SOPPING WET hair. Get a silicone scalp massager thingy and really work the tinted condish into roots and use a wide tooth comb to distribute roots to ends. You’ll have to experiment with how long to leave it on tho. It’s different for everybody. The longer it is, the more tint is deposited.
If you have any questions dm me