At least in US English, “like” is much more common than “as” in these sentences, but I think that both are grammatical and both will be understood.

As a UK English speaker 'as' sounds better on it's own than 'Like' in the first sentences. Although if you're comparing Brazil and another country I would use 'This is very much like HOW we do IT in Brazil' for clarity. As for the second one I would personally say 'This is just like we do in Brazil' because to me it's much more normal nowadays to use just like, than just as, except for certain phrases (like: just as I thought/suspected/planned... which makes you sound like a detective!). Also, just for fun, in UK English 'As you do.', is often said in a slightly sarcastic way to express surprise and to make a joke at the same time when someone tells you about something very out of character they've done or are going to do. For example: 'I bought a new car this morning before work.' - 'As you do!'. 'So I was talking to Amy and we've decided to move to Austria.' - 'As you do!' This is normally followed by A LOT of questions!

use as to talk about job or function. like is a preposition and it’s followed by a noun or a pronoun As and like are prepositions or conjunctions. The prepositions as and like have different meanings. As + noun means ‘in the role of’, like + noun means ‘similar to’ or ‘in the same way as