A new unofficial Tasmota firmware that converts Sonoff ZBBridge gateway into a Zigbee router/repeater has been made available.
ITead's “Sonoff Zigbee 3.0 USB Dongle Plus” model “ZBDongle-E
How to Convert the Sonoff Zigbee Bridge into a Router / Repeater
REQUEST] ESPHome support on Sonoff ZBBridge as a network-attached
Possible to use sonoff wifi ZbBridge as a type of extender, not
Sonoff Wifi/Zigbee bridge – Eiferer_ZA
Third-Party Firmware Turns Sonoff's Low-Cost ZBBridge Into a
Sonoff ZBDongle-E - ZigBee Gateway - USB Interface Botland
SONOFF ZB Dongle-P Zigbee 3.0 USB Dongle Plus Wireless Zigbee
Sonoff ZBBridge - Sonoff Zigbee Bridge from Itead - #137 by
Sonoff ZBBridge WiFi to Zigbee Gateway Launched for $16.90 - CNX
Sonoff Zigbee Bridge Simply as a Router in HE - 🚧 Developers
SONOFF Zigbee Bridge Pro – Sonoff India
REQUEST] Zigbee Router firmware for EFR32MG21 in Sonoff ZBBridge
Sonoff ZB Bridge-p (Pro) to a Zigbee router? : r/homeassistant