Key insight: Revolut and SumUp are among the fintechs investing in Mexico.What's at stake: There are more than 4.5 million small businesses in Mexico, many in the target audience for Revolut and SumUp's payment products.  Forward look: Both firms have plans to expand further in Latin America. The National Banking and Securities Commission and the Bank of Mexico have given London challenger bank Revolut clearance to operate a digital bank in Mexico. Revolut will be allowed to offer a comprehensive menu of fi ...