Nest Doorbell will not connect through Matter, HomeKit or another platform

The checks in more detail

and check Apple's compatibility information for cameras and doorbells before you buy accessories around it. The doorbell's chime inside the house can be linked to smart speakers through Google Home, and the doorbell can announce visitors on Nest displays and speakers in the same Home. In Apple Home, you may find nothing for this device unless a bridge or a feature has been added. If you see an option to add it, the phone must be on the same Wi-Fi, Bluetooth on and the doorbell online, and Apple Home needs a home hub.

If you use a platform with a custom integration, such as a home automation hub that supports Google cameras, follow that hub's instructions and keep the doorbell in Google Home. Do not remove the doorbell from Google Home to try other platforms, because setup would be repeated. For automations, Google Home's own routines can announce visitors and turn on lights when the doorbell detects a person, which covers many needs without another ecosystem. If you need Apple Home specifically, consider a doorbell designed for it. Keep the Google Home app, the doorbell and any hub updated.

Ask Google Nest support or check release notes if you expect a feature that is not available. Test any link by pressing the doorbell and watching whether the other platform responds. Check Google's release notes and the Google Home app's help for any change to platform support, because features are added over time and what is unavailable today may arrive later. If you rely on Apple Home, a doorbell that supports HomeKit Secure Video natively is a better fit. If you are already invested in Google Home, use its routines, which can turn on lights and announce visitors on Nest speakers.