Numbers or letters.

Each team would have their own number system for each pitch
1= fastball
2= slider inside
3= slider outside
And so on

A number like 36284367 would be shown from an digital board from within the dugout before each pitch.

Before the pitcher goes out each inning, they are told.....
“This 3rd inning, we will use the 3rd #”
“Next inning we will use the last number”
And so on....

Is it a different approach??? - yes, but it would eliminate sign stealing (or at least make it harder)