Is it possible to create a message extension that allows for picture upload and for mentioning users

Hello, I'm currently trying to create a message extension for a Teams application and was wondering if it was possible to either mention users or upload pictures in the extension message. For the picture, I was wondering if there was a way to either upload an actual image file or at least paste and image into a text box. I was also wondering if it's possible to mention users in a text box or if it's possible to recreate the functionality similar to the 'Praise' app in Teams that has a dropdown search menu for all the users in the team. Thanks!