Earlier quoted context omitted.
Mono implemented the GUI stuff like Windows Forms, do the latest windows cross platform stuff support that? Can you run .Net GUI windows program on linux without Mono but using the latest .Net thing ? I know it was not possible in the past.
You can use third party libs like Avalonia[1] or Uno[2] [1] https://avaloniaui.net/ [2] https://platform.uno/
My point is about running existing applications on Linux, there are still issues with running .Net GUI stuff under wine and Mono was not a perfect implementation.
I read in other comments that the newer .Net cross platform stuff is not a replacement for Mono for running this old applications. (nobody will rewrite them to use the current GUI stuff from MS since are old apps)