_So using /pt-br/ is fine, what really matter is letting Google know the language/location through search console and other measures what language/location the page are targeting. _
Correct, also, do look into meta tag called "hreflang":
https://moz.com/learn/seo/hreflang-tag
https://support.google.com/webmasters/answer/189077?hl=en
I'm not following what you mean in the last sentence: Unless you use some type of CMS, then you can just use RewriteRule or something to only display needed URL.
Most CMS systems have some type of functionality or plugins, which would let you create content in different languages within the same admin, so you wouldn't have to physically create all subfolders etc. So, whenever CMS does that, it would give you URL, but you might use htaccess rewriterule without redirect to make URL look like you want. Just google "rewrite rule without redirect" and you'll see what i'm talking about.
Hope this clarifies a bit