The highly requested feature is rolling out now; to try it out, open the Android Messages app on your phone, tap the more options menu () select "Messages for web", and follow the on-screen instructions. The page says to use the latest version of the app, but the latest version doesn't let you scan the QR code. Like most Google rollouts it might take some time before your particular phone can fully utilize the feature, but I imagine this will be a much quicker rollout than what Google usually does.
Are you planning on using Android Messages on the web? This is Google's first major step toward "Chat", the company's addition of Rich Communication Services (RCS) inside Android Messages. However, this option section of the Messages app is not live yet, and the service will only become fully available when this happens. As for the other features, they'll be pushed out over the coming week, Google says. At launch, it will support Chrome, Firefox, Safari, and Edge.More news: President Trump orders Pentagon to create a ‘separate but equal’ Space Force
The company also announced a few other features that will come to the Messages app over the next week, including built-in GIF search; Smart Replies, which suggest English language text responses and emoji for now; preview web links in conversations; and the ability to copy one-time passwords with a tap. You can also send and receive messages as long as both devices are connected to an internet connection.
This is a lot like how Google's Allo messaging service works, but considering it's for the stock texting function on so many Android phones, it should catch on quite a bit more.