I also think of Sakic as a more elusive skater, and much more of a passing playmaker than Matthews. Sakic was also a lot smaller (not that he was small, but Matthews is pretty big for a forward).
The biggest similarity is their shot release, that ability to snipe if given any space at all. They kind of occupy the same “role” in the league if that makes sense.
Sakic was so deadly because he was a very smooth skater — not a burner like McDavid or Bure, not a spectacular dangler like Kane — just quick and elusive like maybe Aho or Giroux. Give a guy like that one of the best wrist/snap shot releases of all time, and add a willingness to pass the puck and carry his weight on D, plus that Bergeron/Lidstrom style of quiet leadership, and you have one of the best hockey players ever. There’s really not a guy quite like that in the league at the moment.