You are finally on Android 15 and One-UI 7.
So look at this new feature now.
If your phone supports Smart View miracast connection, then it's a simple solution.This is relative to Samsung Dex, but simpler, and does not require any third-party service if you have these three accessories:
- A Samsung Galaxy smartphone A06 5G, A15, A16, A23, A24, A25, A26, A33, A34, A35, A36, A53, A54, A55, A56 and later versions, excluding Galaxy-S which already has Dex,
- A Miracast-receiving enabled display, a TV which accepts Miracast protocols, or any monitor which accepts Miracast connection. But the Chromecast is not compatible for this feature.
Start by heading over toSettings on your phone,
About phone > Software Information > Build number (Tap this seven times until you accept the prompt.)
Then openDeveloper Options. The toggle 'Force Desktop Mode' is close to the end of all the options. So keep scrolling until you find the toggle.
When you've found Force Desktop Mode, enable it.
It's up to you whether you want to restart your phone or not. There's absolutely no errors if you choose to ignore it.
Get the control ready by only using this app from PlayStore: Touchpad for LG Dual-screen.
Do NOT get any other application for mouse control which requires rooting or debugging which disables security, other than this simple fast app which only requires accessibility: Touchpad for LG Dual-screen.
Read this to the end. And I'll guide you.
Finally, turn on your Samsung TV, (or any other smart TV,) and change the source to Miracast or Smart View receptive mode.

I am using my laptop as an example. Do this in your TV
Select Smart View on Settings on your phone, then select your TV. While they are connected, finally the desktop interface would be running on the screen, starting with a taskbar.
Get to the touchpad application again, and enable permission for system accessibility. Once that it's done, starting using the touchpad.

Your touchpad application.
Write your reviews about this application to the creator of the tool to show your appreciation.
Secondary screen result
If the LG Dual-screen touchpad doesn't seem to be working, then clear the app's data which will reset the application. Then enable the permission again.
The benefits are that you can play videos and movies while responding to messages, or browsing, multitask, or operate apps in an extended view, while your phone saves battery by automatically darkening it's main display.
Use this desktop feature to entertain your family with your living room TV to watch movies, videos, listen to music, and much more, while you resume work on your phone.
If you just want to duplicate your phone screen again, then disable the 'Force Desktop Mode' option, to simply mirror your phone display.
Use Force Desktop Mode at any time. It works. For real. Thanks to Samsung.
Keep reading.
If the Force Desktop Mode is still active on your phone,
Create this routine on Modes, and disable it if you're not using it.

Modes and routines