Thank you, but both TransferWise and Remessa Online do charge fees.
The european bank account I have at Revolut does not charge fees for converting or sending EUR to Brazil in BRL, but it only does work if one can provide BIC / SWIFT
If I open a bank account at Banco Inter (they do have BIC / SWIFT) and send money from my european bank account to Banco Inter and then directly forward to Nubank it should also be free.
but do you know from what amount I have to declare the money somehow (origin) or the bank will ask questions?
Yes, you can @mensa. They might ask you for a few documents. If it’s a salary or a transfer related to business, they have a business version, but you should have a CNPJ. If you need assistance in English, contact them here: firstname.lastname@example.org.