There are several factors that will go into that, but mostly no.
First of all, the Switch have already been selling in Brazil ever since it launched. People who really wanted one already grabbed it, because there are alot of importers over there, and the Grey Market already sells them as cheaply as it is possible, given the currency.
Second of all, Nintendo will never be able to beat the Grey Market prices, which is where most of the sales of (physical) games comes from. Since the Grey Market dosen't pay taxes, and sometimes the goods they sell are stolen, they will offers their products at a lower price than Nintendo ever could, always.
So having them officially sell things here, unless they really go aggressive, will change little. Especially with the gigantic economic recession comming.