[icebraining]

Does anyone actually use it?

It has more than one million five star reviews, so yes.

By the way, while I'd say Google has been definitively abusing its control of the market with Android, I don't think Duo is a good example; I expect a phone to come with a way to make calls, and nowadays I'd include video calls too. Rather than preventing Duo from being preinstalled, the EU should force the industry to come up with a decent open video call protocol.