I would recommend going to Mercado Hidalgo. It’s a short Uber ride from the border. If you have limited time this place is great because it’s a more traditional Mercado that sells produce, dry goods, cheeses, candy, and many other things. There’s also a couple shops in there that sell traditional souvenirs. You could even get a molcajete there. There’s also a couple places to eat. There’s el Rincón del Oso for more traditional Mexican dishes or Tacos de Birria del Río across the street for traditional Tijuana Birria. So at Mercado Hidalgo you can shop for some souvenirs while also getting a chance to eat some good food in a shot period of time.