Sorry but no. The code is not opensource unfortunately.
When you follow the Learning Paths in the Academy you can download Project packages and Module packages, but the best you can do is just follow the Learning Path from start to end.
Sometimes the sources can be downloaded if the builder allows it. For example Bootstrap Input Addons (https://github.com/JAM-IT-NL/MendixBootstrapInputAddons/releases/tag/3.3.4)
You can also search the appstore for example projects.
Thank you for your interest in the App Gallery. My team manages and develops the content on the App Gallery. The applications have been built to inspire users as to what is Art of the Possible with Mendix. Currently these apps are only available as demos because they contain some complex concepts, which we would like to explain before releasing them.
We are aware that many of the community would like to see more example projects. Once i have more information i will share here.
Lucas is there a particular feature of that app you are more interested in? I can perhaps point you in the right direction to recreate it.