Neither microblogging nor forum discussion are popular in Brazil; the top contenders are video services (YT, TT), and the Meta cancer tendrils (IG, FB) behaving as Orkut replacement goldfish. So the main Fediverse services are alternatives for things that, locally, are not overly common to begin with, when people have their “motherfucking caramel” doing funny shit they beeline for TT or FB.
Another factor that I think that reduces Fediverse usage in Brazil is Anglocentrism. Brazilians are mostly monolingual; the exceptions are typically 1) from a colonial background, or 2) highly educated, and only (2) applies here. For most people in Brazil, English content is the same as nothing, or as “the skwerlficashun! throovy! afdsjkfdsa!”.
That backtracks into your OP. I believe that Fediverse success requires
diversification of the platforms widely used and available in the Fediverse
better ways to handle language that reduce the “I don’t speak it so it’s noise” issue
Even with that in mind my city has a Mastodon server. I often lurk there because I’m a verbose fuck, not suited for microblogging; but it’s comfy.