dont buy ecobee
waste for what you want
buy a basic thermostat
Radio Thermostat CT50 7-Day Programmable Thermostat (WiFi Enabled), iOS & Android App Controls Amazon.com
there is a smart app developed by a developer in the forum
i know the app says it works with 3m-50, but its the WiFI module that it works with that the thermostat above has. you can buy used for $60
dont have a c-wire? no problem
you will need this
Venstar ACC0410 Add-A-Wire Accessory for All 24 VAC Thermostats (4 to 5 Wires), White Amazon.com
you cant run a zwave or wifi thermostat needed for a smart home without a c wire. the batteries would depleted so fast
heres a how to video for the ‘add a wire’ device
there are other how to videos without buying a device but i dont recommend bc you would lose functionality typically of the thermostat fan.
the venstar device gives you all functionality
great news is since the thermostats will be compatible with smartthings then it will be with alexa too.
hopefully you understand this solves every problem🙂