Brazilian here, he can't and for a good reason: The entire process for PIX, from initial engineering to final implementation is documented and made public.

The government is making this for the exact reason someone else mentioned: We're at the mercy for a handful of big players, and that's enough. One open standard for all is good. (Edit: It's also an "economy" controlling standard. Not aimed at end users. It's something for the Central Bank to keep notes on what's happening with the money going around.)

The documentation sadly is in portuguese and in PDF: https://www.bcb.gov.br/content/estabilidadefinanceira/forump...

You can find more by looking on Google for: Banco Central PIX PDF

Personal note: A lot of people sadly still believe everything the government makes equals bad or equals to something that was idealized/created by the current president in office. It's not the case here by any means (the Brazilian Central Bank runs "independently") but unfortunately a lot of people see it that way.

Great! Just make PIX an alternative to the market, not something mandatory.

That's not possible for products that rely on social networks. Facebook has a monopoly in communication in Brazil, and if they had to compete with Pix they'd win regardless of the product. Pix, however, means anyone can integrate the functionality in their application, making every service compatible with each other and increasing competitiviness.