Brazilian Pix is free though, at least for the time being. IMO the biggest thing is not the money behind it, but the ability to track individual payments. Even that, I prefer the government to have that information, than some shady owner of a private company
PIX are free for persons.
Companies may* pay for pix services. My bank (that is not a good bank) charges a fixed amount of 4 BRL (aprox 1 USD) per transaction (to send PIX. not to receive)
PIX in "maquininhas" may cost ~1% to the seller.
To give some reference, using stripe you pay 2-3% for credit card payments and PayPal charges you ~5% of the transaction amount. Apple store and Steam take 30%. So honestly 1% sounds like a great deal.
I think comparing Steam and to some extend Apple with payment methods, they are stores and it cost money to store apps and games and for this one I'm not 100% sure, but I read a while ago that they also pay taxes for you in the country you sell, while pure payment processing services are just a proxy to move money from one account to another. You could argue that 30% is high for that, but we aren't discussing it here.