They're just storing doubles in their own format too. I'm not sure if they even need any spatial lookups on the data, they didn't mention anything about that in the article. Maybe they do that in-memory?

Aren't time series databases like Prometheus pretty good at storing this kind of data?

That "DRM the web" proposal can go die in a fire.

They are really trying to make a server not serve you anything until your device is deemed worthy by Google play or some other shitty software?

Fuck that.