GoControl has a zwave thermostat that works well. Has no smarts of it's own (behaves like a pretty standard thermostat with heat, cool, and fan settings) but can be changed via home assistant so I've written a pretty extensive algorithm to meet my needs.

Honeywell T6 Pro

https://www.amazon.com/Honeywell-Intrusion-TH6320ZW2003/dp/B...

I have two of these (for separate HVAC systems on top and bottom floors of my house) and can highly recommend

The killer feature of Home Assistant vs. my previous Nest setup came when I added door and window sensors, and programmed HA to pause heating/AC whenever doors or windows are open. I no longer turn into my father, who I remember shouting at us kids, "close the door, I'm not paying to air condition the outside!"

ecobee works locally (without its cloud services) through Apple HomeKit.

I have an ecobee. Quite nice and easy to program on the panel itself if you choose not to connect it to your wifi at all.

One oddity with my ecobee - if it's not connected to wifi, the clock runs fast. Sometimes gaining a whole minute every few days.

Cheap oscillator because they expect it to be network connected and be corrected by NTP. Why put in a good clock when a cheap one will do?