I got the Meross Smart Matter+Wi-Fi Thermostat MTS300 US running today.
In case anyone is curious about what gets exposed to Home Assistant, here it is!
The installation was some what haphazard. I think I was supposed to install with the Meross app. But I'm not sure if that actually was needed. I think I installed via scanning the Matter code in Home Assistant... and then later it appeared in the Meross app. 🤷
The Meross app exposes fan controls. Also child lock. You can also create a schedule in the Meross app. None of these features are visible in HA. (Also cannot control display brightness via HA. Sad.)
Side question: how do y'all create a schedule for your thermostats? I feel like I shouldn't use Meross' scheduling features and I should keep all the smarts in HA, right? I guess I should create Automations and trigger them based on time of day?
Update 12 Nov 2025
Meross released new firmware! I updated my (now 2) thermostats to firmware 9.1.14.1.2.2 and I have fan control now!!! 🥳
I have a template called Advanced Heating Control v5 which works like a charm. Only thing in struggling with is that my TRVs can't control the boiler so they only receive hot water once the temperature in my living room drops below my comfort temp.
https://community.home-assistant.io/t/advanced-heating-control/469873