That thread is just the result of a search today to see if the situation has changed.
When I tried it, we were still trying to figure out how the two displays worked. It looks like that link has a solution. It would have been great to try back then, but I wouldn’t go out and buy a 5k iMac or LG monitor just to try it out now.
Ubuntu was a successful attempt to make Debian user-friendly. If you don’t remember Linux in 2003, it took a lot of time to configure.
Ubuntu came along and did everything automatically from first install. Some of the polish it had was things like smooth fonts, TrueType font support (remember old XFree86 Bitmap fonts?) a GUI installer, automatically detecting your monitor resolution, setting up sound automatically, and automatic downloading of firmware needed to make your hardware work. In just one reboot after install, you had a usable system that looked really nice, with smooth fonts.
In 2024, Debian already does all of this out of the box. The value add of Ubuntu is minimal. Ubuntu provides a theme, a splash screen when booting up, a custom font, and a modified version of the Dash to Dock extension that you can just download yourself from the Gnome extension site. That’s it. One might argue that snaps make Ubuntu worse than Debian.
Just use Debian. If you want a somewhat more polished system (nice cursors, unique icons, easy to configure animations), there is Mint Debian edition.
It takes less time to just set up Debian to look and behave like Ubuntu (about 10 minutes) than it takes to continually fight against Ubuntu snaps.
Just use Debian.