Even though Google's messaging app didn't really meet up to expectations, Google isn't actually giving up on the app yet as they are pushing out updates with many more new features.

Google has just added an option to share and receive files with the Allo messaging app. At the moment, the list of supported file formats are apk, zip, pdf, .doc and .mp3.

How to Share Files on Google Allo
=> Open any conversation and click on the "+" sign at the bottom left corner of your screen.
=> Click on the paper clip icon and this will open your phone's file explorer.
=> Just select the file you want to send and click on. "send now".
That's all guys.

Also, there are speculations that Google might soon add stickers to the Allo messaging app, but there is no confirmation on that yet, so we just have to wait.