Duo is pretty good actually, but to answer your question, I haven't been asked to use it, although I have used it a few times with people I know well . In terms of cross-platform apps, it's one of the better ones, but far more people will have Messenger or WhatsApp installed. These days it's lunch is being eaten by Zoom (and partly Teams) as well, and in typical Google fashion, they have signalled that they will over time roll it into their Meets product, which I don't find particularly good compared to Teams/Zoom.
I kind of wish it had taken more hold as a cross-platform Facetime alternative. I don't like proprietary messaging tools, and trust Google more than Facebook.
Simen