I've been wondering about smart lighting (maybe smart sockets and other
stuff) but wanting to avoid proprietary lock-in. I know Philips Hue and
Ikea Tradfri are actually zigbee based and have limited levels of
interoperability, also a certain amount of hacking can be done, but not
necessarily wanting to go the home-brew route.

This seems to be a significant announcement to open things up ...

https://www.connectedhomeip.com
https://zigbeealliance.org/news_and_articles/connectedhomeIP