FYI, for reference, someone else also asked/discuss the same here → Migration from Hue to ZHA
As far as I know there is no migration path to migrate existing Hue scenes to Home Assistant’s own scenes. And do note that Home Assistant’s “scenes” are not directly related to ZHA as Home Assistant’s “scenes” can be used with any type of devices and are not specific to ZHA or Zigbee.
As such you can use Hue devices in ZHA just like you can use any Zigbee devices with it, but ZHA does not integrate with Hue ecosystem in any way and those Hue scenes only exist in Hue ecosystem. So I think that you have to replicate those scenes from scratch with Home Assistant’s own scenes and automations.