PIX is Brazil's domestic instant-payments rail, operated by the Banco Central do Brasil. The rail is 24/7, settled in seconds, and was launched in November 2020 as a native ISO 20022 system from day one.
PIX uses a customer-facing key system (CPF / CNPJ / email / phone / random key) that abstracts the underlying IBAN-equivalent account number. The customer-bank API is REST + JSON for instruction submission, with ISO 20022 pacs.008 + pacs.002 underneath for inter-bank settlement.
The relevance to iso-compliant: PIX is the cleanest production example of a native ISO 20022 instant rail and is widely studied as a reference model for the EU SCT Inst evolution and the US RTP rail. iso-compliant does not cover PIX today; the value of mentioning it here is correctness and search-discoverability for a researcher comparing instant-payment rails.