Where to buy a Brazil SIM/Chip at GRU - Answer
 

After being directed to countless shops, floors, and terminals I finally found where you can buy a Brazilian SIM card. It's in terminal 2 (B area) near the entrance to 200 numbers gates. On the top floor look for the Starbucks (this is a bit tricky as there are multiple but separate top floor sections and a Starbucks on the main level), go up the escalator and turn towards the two banks, go right down the hallway about 100 feet and there is a lotteria office. They sell them there. Mine was 30 real for the chip and 1 GB lasting 1 week for TIM but can be topped off when needed. There are probably better deals at the stores in the city.

There are a couple kiosks that sell one month internet for $100 usd and another that sells a year long WhatsApp for $25 usd both I think are overpriced.

Hopefully this saves time for someone.

Not sure why but my first time in GRU they wouldn't sell me one. I just got a guaracoop and grab one at Vivo in one of the many malls. Pre-pago, bring your passport.

Found the loteria!
 

It's actually between check-in location D and E.
They still sell local SIM as of January 2020 however only to residents.
I'll try my luck in one of the local vivo offices...