For the Mouse Pointer to stay in the window, we will change the "Allow edge swipe" policy setting and launch the game in Fullscreen mode on a single monitor.

Prerequisites: Local Group Policy Editor (not included in Windows Home)

1. Press WIN+R
2. Type "gpedit.msc" in the box
3. Press "OK"
4. Navigate to "Local Computer Policy>Computer Configuration>Administrative Templates>Windows Components>Edge UI>Allow edge swipe"
5. Press "Edit policy setting"
6. Select "Disabled"
7. Press "Apply"
8. Press WIN+P
9. Select "PC screen only"
10. Launch the Game / Program
11. Press F11 (alternatively navigate to "Settings>Video>Fullscreen" and make sure it's switched on.)

Now the Title- and Taskbar should stay hidden with every mouse movement.

I think this is the only workaround that works for Windows Apps so the Mouse Pointer stays in the window.

If there is anything I forgot, something I can add or another way to achieve this, let me know in the comments or shoot me a message!