An envelope tracking (ET) amplifier apparatus is provided. The ET amplifier apparatus includes an ET integrated circuit (ETIC) and a distributed ETIC (DETIC) coupled to a single-wire bus that correspond to a first bus access priority and a second bus access priority, respectively. The ETIC and the DETIC can contend for access to the single-wire bus by asserting a bus contention indication(s) when the single-wire bus is in a defined bus state configured to permit bus contention. In a non-limiting example, a winner for the single-wire bus is a peer device having a highest bus access priority between the ETIC and the DETIC. In this regard, each of the ETIC and the DETIC can have a chance to initiate communications over the single-wire bus, thus making it possible for the single-wire bus to function based on bidirectional peer-to-peer (P2P) bus architecture capable of supporting more application and/or deployment scenarios.