I’m overall no fan of GG, but it seems (speaking as an outsider) he had the goods on Bolsonaro before the election, and his husband is now in the literal firing line as a gay, liberal Congressman in a time of rising right-wing violence. I’m not sure Greenwald has been effective or even all that salutary in regards to US politics and policies, but he might just be the journalist Brazil needs now.
Unfortunately, most of what is produced in Brazil is just the opinion of the journalist or, worse, his boss's. In fact, a local journalist once admitted the only thing he ever read was his own paper and nobody thought anything of it (Paulo Sant'Ana from Zero Hora). If you think about it, the big names in Brazil, like the recently deceased Boechat or Reinaldo Azevedo, spend all day in different medias. Where would they get the time to investigate anything?