Nest Thermostat Gen 1 or Gen 2 running NoLongerEvil firmware. You can pick up a gen 2 on eBay for 20-30 USD. It only takes 5 min to load the and there is a HA native integration. Rock solid hardware with no cloud, no google, and it works great with HA. Note that the gen 1 and gen 2 are pre Google buyout of Nest. There is also a cloud hoisted dashboard if you want BUT there is self-hoisted docker and HA only versions as well.

nolongerevil.com