Exactly this. The device either needs to be open enough that it can easily integrate to HA without internet access.
Or dumb enough that I can mod it with an ESP.
Anything that has to go through the manufacturer’s servers goes in the bin, the risks of data theft/rent seeking are too damned high.
Very accurate.
When we had the northern lights here, we pulled over on the way to the dark-sky location, and the aurora filled the sky.
After it died back a bit, we drove on to the dark-sky, where we spent 3 hours sitting in the dark working out if the green bits were going to spike up again.