Look into custom ROMs for galaxy s9. This one is running Lineage OS 20 with microG (other options include Noble ROM, Duhan ROM, Floyd ROM)
Unlock developer options to allow home screen rotation, change colors of light indicators, or add taskbar by increasing screen density to 600 (android 12L+)
Change the default launcher for a more modern home screen.
With this ROM, desktop mode actually works very well (connecting phone to a monitor via hdmi), but you might experience flickering. This is easily fixable, just disable HW overlays in developer options.