I'm using this small OrangePI hub for a while now and it's pretty neat and useful to link the 'Nest' ecosystem back to Homekit without headaches.
At the beginning, I was using two separate homebridge npms (one for the thermostats/protects and one for the cameras) but Adrian built Starling and he is making easy enhancements and a working device.
Of course, as it's based on a small OrangePI, don't expect a 'speed of light' but you can get your content from homekit easily and have other members of the family able to use all this home automation with a single app on their phones.
You will also need a nice Internet connection to have it working seamlessly as (by design from Nest), you cameras are streaming to the cloud and Starling will get the content from the cloud also. Bottom line, if you're not at home, looking at the content of a camera, you will then go the the cloud/home ..... three times:
Camera (at home) ==> upload to cloud
Starling (at home) <== download from the cloud
Phone with Homekit <== download from starling (at home)
Overall, I'm really happy to have this device running, I have 9 thermostats, 12 cameras and two protects, and recently, Adrian added Airplay (v1) to the speakers and you know what..... it's working ;-)