I have an ecobee I mainly control locally through the HomeKit integration on HA. Just about all of the basic features are covered: setpoints, heat/cool/auto/off and fan on/off/auto. Some of the more advanced features like Home/Away/Sleep profiles are not available through the integration, but they tend to be set & forget.
It doesn't need Internet access or the companion app to operate your system, though it will use external access to track local weather and energy rates. (And probably collect usage data.) The companion app gives access to a few more features remotely, but the unit is completely programmable from its front panel.
It's worked out fine for me so far. My local power utility sells them at a steep discount through their online storefront. Check around for rebates.