My condolences, that sucks that you’re stuck in such an authoritarian country. If you look at the PostmarketOS site, you may be able to find a legal phone (weird to type that phrase) that can be reflashed. Or you could buy one while on vacation, my guess is they don’t check models at the border if it looks like a personal device.
Illegal in Brazil per the Digital Child and Adolescent Statute. Operating systems are legally required to provide age verification functionality in a manner approved by the government.
Edit: apparently if it isn’t a “marketable product” then the law may not apply. So far they haven’t enforced it against Linux distros, likely because of this exception. However, IANAL (and definitely not a Brazilian lawyer).
Indeed, and since Brazil now has mandatory age checking in the OS, it's illegal to own or operate such phones in the country, thus they will never be certified by ANATEL.