What exactly are you looking for in a door sensor. Is it a contact sensor that will just tell you if the door is open or closed? Or is it a tilt sensor that will tell you when a door is moving?
The reason I ask is that there are a couple of different options, but it depends on the specific use case.
Quite a few people in Canada or Minnesota have used a nonnetworked gate sensor for open/close and then run its contacts to a smart things – compatible sensor inside the house. It’s similar to what people do with doorbells. That can work quite well and we’ve discussed some of the options previously.
And then you would connect it to a networked sensor in the same way that people do for a pressure Mat:
If you’re looking for a tilt sensor, the Kumo wireless tags are an option. They can be used even inside the freezer and have an operating range going down to -40 Fahrenheit. There’s a community – created device type handler for them. Each tag cost about $40 and you also have to buy their ethernet bridge for $60 (one Bridge for up to 40 tags).