Open Document Action: Pointing to Alias

Yes, this can be done, but I would not do it using file alias or symlink.
Creating these requires too many steps.

I would just use two macros:

  1. Macro #1 would set the path to the target document to a KM Global Variable, using the KM Action Prompt for File.
  2. Macro #1 would open the file in the above KM Global Variable.

You could even make this with one Macro, but with an option that uses long press key to set the KM Variable containing the path.
See MACRO: Trigger Option Using Long Press of HotKey [Example].