When I got my new HVAC system installed a few months ago (heat pump, woohoo!), they needed to upgrade my thermostat, so they gave me a Honeywell VisionPro 8000,

When I got my new HVAC system installed a few months ago (heat pump, woohoo!), they needed to upgrade my thermostat, so they gave me a Honeywell VisionPro 8000, which is a "smart" thermostat but, like your T9 (I think), demands WiFi and some garbage "cloud" service to access the connected features. I replaced it with a T6 Pro, a thermostat which is by all other metrics a downgrade, but which has a single killer feature: Z-Wave. No phoning home, no janky embedded devices on my WiFi network, just a solid integration with Home Assistant that falls back to a regular thermostat if my HA server is down. Seems like Honeywell is moving away from making Z-Wave versions of their products, because I think most consumers are generally content to tunnel their request through some shitty cloud thing every time they want to turn the heat up... but for those of us who are a little more ideologically rigid about keeping their stuff LAN-only, would definitely recommend grabbing a T6 Pro while they're out there.