Array Cartesian product in bash

Is there a means to create cartesian item of selections without making use of loopholes in bash?

One can make use of curly brackets to do a comparable thing:

echo {a,b,c}+{1,2,3}
a+1 a+2 a+3 b+1 b+2 b+3 c+1 c+2 c+3

yet I require to make use of selections as inputs, and also the majority of noticeable methods fail me.