Hi @hamza !
As explained this is due to privacy reasons, the DHIS2 Android App follows the OWASP security principles and so some of the features that you might find in other applications are not allowed. You can read more about this in the OWASP MSTG
If you need the full features of the Application we recommend using the Training App as they explained. That will allow you to perform these tasks (screenshots, working on root phone, etc).
However, as @prcleary mention. We find scrcpy so useful that we event recommend it for testing, training, etc… we wrote a post about it! How to clone your Android screen (useful for: presentations, debugging, etc)