In this case I think the multi-device syncing capability is the thing that adds value. Or at least being able to sync the data gathered by the device to the clo

In this case I think the multi-device syncing capability is the thing that adds value. Or at least being able to sync the data gathered by the device to the cloud so you can access it through a separate interface. If that is the case then whether you prefer a Google solution to a open source solution depends very much on your threat model. Google may use that data to target ads but running your own solution you risk losing the raw data to a security flaw in the open source code or infrastructure. At least with Google you get world class infosec to protect your data (from everyone except Google...)