Not clear by your question exactly what you want to migrate from or what you want to migrate to?
To clarify one thing first; it is not supported to migrate from Zigbee2MQTT to the ZHA integration, or vice versa. If you want to move from Zigbee2MQTT to the ZHA integration then the currently is no other migration path than to remove each device from Zigbee2MQTT, then factory reset each device following the manufacturer’s instructions for that, and only then join/pair the device to the ZHA integration, i.ei. doing it all from scratch. And the same thing goes if want to move from the ZHA integration to Zigbee2MQTT.
So assuming that you instead just want to migrate from another Zigbee Coordinator adapter in Zigbee2MQTT to the Home Assistant SkyConnect as Zigbee Coordinator adapter in Zigbee2MQTT (or vice versa) then see this related discussion in the Zigbee2MQTT community → https://github.com/Koenkk/zigbee2mqtt/discussions/16478