ZHA developers are working on it and puddly has just implemented an the need API in the underlying zigpy library that was lacking to make it happen → Implement an API to change channels by puddly · Pull Request #1190 · zigpy/zigpy · GitHub
Home Assistant core ZHA component and Home Assistant’s frontend UI implementations is still missing however sure that it will be prioritized next now that the underlying work is done.
Also note that there is not yet support for it in alla zigpy radio libraries and different radios / Zigbee stacks will handle it differently. So far it sounds as if the znp radio library for Texas Instruments radios will work best, at least so far:
PS: You should not really have the need to change the Zigbee channel unless your neighbours have stong WiFi that you can not change. Read and follow all of these tips regardless → Guide for Zigbee interference avoidance and network range/coverage optimization