[barnas2]

That's what I did. Just an esp32 relay board with a tiny screen and a knob. Then I put more esp32 sensors in each room to get individual temps, with HA logic to select which room the thermostat pays attention to. If HA dies for some reason it falls back to a local control and I'm back to the same situation as before, a thermostat that only pays attention to the temperature in the hallway it's installed in. All the boards were flashed with ESPHome.

[scottlamb]

Nice. I don't have any ESPHome thermostats right now, but I have an ESPHome fridge/freezer temperature monitor. I adopted the same idea: it should integrate with HA when HA is available, but it should be useful even when HA is down. So in addition to exporting the raw temperature to HA, the alert threshold is kept on the device rather than in HA so it can locally compute the alert state. This triggers a directly wired piezo buzzer, in addition to an HA phone notification.

You do have to set the "api: reboot_timeout: 0" if you don't want it to reboot itself every 15 minutes while HA is down. I persisted the alert threshold to flash though so even if it does reboot it comes right back up and works fine.