AG Mouse app will let you use your phone as the air mouse for Samsung DeX mode with TV or monitor (not for Samsung Dex app for PC).
This app does not require root access.
This app uses AccessibilityService API to read gyroscope sensor data to navigate the mouse cursor on the screen as the app feature. By pressing "Allow" button in the "Ask for permission" dialog when opening this app, user allows this app to use AccessibilityService API. Otherwise, pressing "Exit" button to deny and stop using it.
The recommendation is to use this app for Samsung phones with the supporting DeX mode with Android 11 and newer because it was tested very carefully on these devices and these Android versions. However, the app works for other devices like Google Pixel and other lower Android versions but not all of devices and Android versions were tested. (Please be noted that before buying it and please don't give bad comments due to using it on unrecommended devices and Android versions)
This app requires the API from Shizuku app. So user need to install Shizuku app on Google Play store as specified in below link.
Shizuku app: https://play.google.com/store/search?q=shizuku&c=apps
All other information about how to setup and use this app can be known in the above video or the video link below
Video: https://youtu.be/cv12u6Zf7ms