Yes and no. Zigbee is not Matter/Thread, so you should ignore it. But Zigbee can be local as well. Most of the commercial solutions (like Tuya, Sonoff, Smartthings) put all the logic in the cloud as it is easier to serve the same functions to thousands of customers. But there are other solutions where the logic is local and it talks to the zigbee devices locally. Matter/Thread is great, but so far I have seen smart plugs, light bulb, light switches and that's more or less all. No door sensors, motion sensors, temperature sensors, etc. That limits the what you can build with Matter/Thread only.

@@csongorvarga Thanks for the quick reply! I'm looking at the light switch Sonoff MiniR4M but then realised that it can only do on/off and doesn't have a dimming function for example. I expect them to bring on the market more advanced devices like sensors that you mentioned. Are you optimistic about it in the next year or so? And yes, I'm looking for a local setup, or at least more secure and not dependent on various cloud(s). I'm considering using my Qnap NAS as a "cloud" replacement. Thanks for your advice!

I am getting one. I guess it is not released yet.

I don't have an extensive Zigbee network to see any issues with it. Both of them are working fine, both of them have turbo mode, I would say it is comperable, but the external antenna of the Ultra must be somewhat better.

No, the Matter sharing only applies to the Zigbee devices. M5 is not zigbee, it is a wifi switch.