I was searching for the answer to the same question. What I did was to stop deconz, start up the ZHA integration and start working. It took ZHA an hour to get through my 100+ devices. At first, it didn’t find any battery devices, but waking them manually did the trick.
The neat thing is that all lights and devices found by ZHA magically appear under the same device tab as deconz entities, which makes it easy to rename them to your old entity. Doing so, no need to mod any automations given you are copying the same entity id from the old device.
To not break anything, I renamed my deconz-entities with a _old suffix, if I need to switch back.
So, 1) stop deconz (I ran deconz inside my HA install so I only stopped the add-on, not the integration) 2. Fire up ZHA and let it discover all devices automatically 3) rename all devices. Now you’re running ZHA.
Good luck!
Edit: Oh, and make a backup for your deconz-config in Phoscon. Menu > Gateway > Backup Options. Just in case!