Sadly, unlike WhatsApp Web, Google Allo doesn't work simultaneously on Web and Phone. As the site explains, Allo "learns if you're more of a "haha" or "lol" person so the more you use Allo, the more "you" the suggestions become".
Do you plan on using Allo on the web?
We should be really close. Google revealed the new web app today, allowing those on Android to pair their phones with their computers and send messages from there. However, the Google Allo is still in the early form to be used on the web and there's plenty that still has to be developed. If you normally browse with Firefox, Safari or Edge, you'll need to fire up Chrome or opt to continue without Allo web. You need to click in the menu on your mobile device to see the web option of Allo. The two are connected in a similar manner in which WhatsApp for Android and WhatsApp for desktops are, requiring users to scan a QR code rendered by the browser client with their mobile app before being allowed to use the service.
That's doubly true when you realize that your phone needs to be continuously paired with your computer in order to use the web app.
And that's pretty much it. The way the app works also prevents you from switching between Google accounts or even deleting a conversation.
The User Interface (UI) for Allo for the web is nearly similar to the mobile application which allows emojis, smart replies, stickers, and media sharing. You will not have access to notifications and privacy settings. Additionally, you lose out on one of Allo's best features, an iMessage-style animation that indicates the other person in your conversation is typing. Well, for this reason, the new Google Allo for Web doesn't include the ability to launch a Duo call from within the client.