This is similar to allowing global variables to be defined in a sheet, but is not actually the same thing.
Basically I am asking for access to variables in other sheets like you can do in a spreadsheet like Excel or Google Sheets. This would mean a sheet would need a name, likely the heading but it would be good if a user could optionally give is a more concise name, maybe like the first image.
Then in another sheet be able to reference those variables with a qualified reference something like in the second image.