Google seems to be preparing to launch Duo on the web soon. A few users and developers have reported that they could make calls over Google Duo in Chrome, Firefox and Safari browsers.
Yes, Google Duo now allows you to initiate video calls from your desktop web browser. You’ll also get a notification alert on your desktop when you receive an incoming call. The change is still rolling out from the server side so it may still not work for everyone. Most Chrome users are having no problem accessing it via their non-G Suite accounts.
The main interface is fairly simple with a few recent contacts listed at the top and a full list of all contacts from your Google Contacts list below.
Google is still yet to formally announce Duo for desktop.