Duo is pretty big. It's pre-installed on every single android phone, and on Samsung phones it is the default video calling app too.

Also, you cannot remove it. You can uninstall the icon, but the underlying code is so deeply integrated into the OS that people can still call you and you will get a Duo video call even after uninstalling it.

Quite a menace.

That's actually (at least recently) quite "popular" product I would say, because they included it in most Android smartphones to offer video calls. I am tempted to say Google Duo is spread on millions of devices, however it is kind of an app, which is rarely used at all by most of users. Also, there are thousands of competitors, where even Google Meet does feels better than Duo.

Seems like an incomplete list because Google Poly is not on there. I double checked archive.org to make sure it wasn't removed today.