I'm not a homeowner - is it normal to have this many radiators in a house this size? My 2BR apartment has one thermostat and my parent's 4BR house has one as well.
IIRC, if you do not have central heat, then you have a radiator in every room you want heated. Each radiator is then going to have its own thermostat to control its heat level for that room.
Some houses have central heating where one thermostat controls the entire house. My rental which was built 3 years ago has that. That is a case where I think something like nest is affordable and useful.