I've used two of these and they are quite accurate. At least accurate enough to set high and low alarms.
The two $29 ones in the following link are the ones I've used.
https://www.thermoworks.com/Alarms/Fridge-Alarms
Be careful of the wires. They are fragile.
I paired them with a cheap remote baby monitor so if I was in another place on the property I could hear the alarms.
The wattage or amperage of the incubator should be on a label either on the bottom, by the controller or near the wire entering the incubator.
If you give me the name and model of the incubator I could look it up.