but for example people from South America

/me raises hand

That said I think that it's better to create instances for languages than countries. Three reasons:

1. It's language that dictates availability of a piece of content for the user.
2. It encourages linguistic minorities to help us to grow the Fediverse. Reddit doesn't give a fuck about them because they aren't profitable merchandise=users for its customers=advertisers, but Lemmy isn't bound to that.
3. Some people would rather use their L2, L3 etc.

A good example of that is feddit.de - note how the instance targets German speakers, not people from Germany.

Are you from there? Or do you want to do missionary work for other parts of the world?

Because I would need some more information on the 'target' people. What kind of social media do they use currently in that country? Is Reddit even a thing there or do people there maybe don't even need a good alternative to that? Maybe they like to spend their time on Twitter / Mastodon over there.

I know there are quite some Japanese people on Misskey. And I've seen lots of Spanish and French content on Peertube.

Ah yes. And you absolutely need admins/moderators who speak the language.

Setup a server and advertise it on here.

Be the change you want to see.