In a sense, Trump's rant against Pix is promoting it to the world. Moreover, some stores in Portugal and more recently France are accepting Pix as form of payment.
It's not a small population. There's estimated 40k Brazilians in the Netherlands for example, most of them illegal. They need a payment system which doesn't require a European bank account.
PS: I don't think anyone is illegal, but the system push them out.
Generally, yes. You need an account in some Brazilian bank to use PIX, so these are likely Brazilian nationals living abroad and accepting payments directly to their Brazilian accounts.
PS: I don't think anyone is illegal, but the system push them out.