Home Assistant’s serial guide walks through connecting equipment such as an AV receiver or energy meter either by a nearby USB adapter or through an ESPHome device beside the equipment. It explains how to check the available ports and choose the connection in the equipment’s integration.
The guide recommends stable serial identifiers instead of numbered USB paths that can change. A companion ESPHome overview explains Bluetooth, infrared, radio and serial proxies, and makes clear that serial proxies require a configuration you write and install yourself.