Itead has just launched Sonoff ZBBridge which is an inexpensive Sonoff Zigbee Bridge which is based on a similar design as their Sonoff RF Bridge
According to the teardown and notes on notenoughtech.com and cnx-software.com it sounds as if it is based on Silicon Labs EFR32MG21 (EFR32 Mighty Gecko) for Zigbee 3.0 radio module support and ESP8266 (ESP8266EX) for WiFi and bridge/gateway/controller software
By default it uses the eWelink cloud but hopefully we will sooner or later see support for third-party ESP8266 firmware from projects like Tasmota for local control. (Tasmota’s Zigbee2Tasmota sub-project has for example support acting as a Zigbee to MQTT bridge via a Texas Instruments CC2530 radio module similar to Zigbee2MQTT)
From the images it also looks like Itead is even reusing the same injection moulds as for the Sonoff RF Bridge 433 housing/enclosure, and popular third-party ESP8266 firmware projects like ESPHome, Tasmota, and ESPurna already has support for that existing Sonoff RF Bridge, including RF control.