> To be able to pay with Pix, one needs to get a CPF (Brazilian Tax ID).

There are third party apps you can use to pay with pix using a credit card, can't recall that name, but read about it here a few months back, on another pix-thread.

> CPF (Brazilian Tax ID). Then to open a bank account

Getting a CPF is absolutely trivial, but I'm not sure you can open a bank account without RN/RNE, at least not with local banks. Can probably manage with one of the online banks.