The new SNZB-04P from Sonoff is still not supported by Homey! This simple device is great as the sensors can be placed at greater distance and therefor be used on double glass windows/doors. Hopefully the support will be available soon.
Also I miss support/integration with M-Air (Mitsubishi AC).
Do you already have a Homey Bridge or a Homey Pro in use? Did you check which devices are supported before buying?
If you are missing devices in an existing app, please contact the app developer. There are contact options for almost every app in the App Store.
If you are missing support for a device for which no app exists yet, you can submit a request in the forum or to Athom. Where and how this is possible is explained in the Welcome to the forum! topic.
Edit
Btw, there will never be a guarantee that the device or manufacturer will be supported in the future.
Additionally:
If it were a Matter device, there’s no need for an app.
@Kenneth_Madsen There are so many devices out there, you happened to pick a (still) unsupported one.
With stronger magnets, any contact sensor can be used on bigger gaps.
Here’s a list of “best buy” contact sensors
https://homey.app/en-nl/best-buy-guide/door-and-window-sensors/
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Tried the onboard IR remotes already?
Not sure why there’s 4 entries of “code group 1” 
In this case it is Sonoff which is supposed to be supported. It is just an upgraded and improved version of an old product SNZB-04, which are supported.
It doesn’t make no big difference whether it is a completely new device or a new improved version of an existing device. Both devices must be added to the code.
It may be that the code for the improved version can be copied from the previous model and only 1 or 2 changes need to be made. But this also has to be done.
Therefore, please contact the app developer.
