Need to reuse the same chart or map in another project? Easy!
Select the chart or map you wish to copy. Use keyboard controls Cmd+C (on Mac) or Ctrl+C (on Windows).
Go to another project and paste the object using keyboard controls Cmd+V (on Mac) or Ctrl+V (on Windows).
The chart or map will appear at the bottom of the project. Go into chart settings to reset colors, as the object will retain the formatting of the current theme.
Note that copying elements between projects is not possible for the Table chart and text objects.