Answer by mikado for Applying several functions to the same argument

I think that in Version 14, you would be able to write

fn = Comap[{f1, f2}]@*(Exponent[#, Variables[expr]] &)

With this definition, you would the have

expr = a + b + c(* a + b + c *)fn[expr](* Comap[{f1, f2}][{1, 1, 1}] *)

which I think would be what you wanted (if Comap were defined).

I haven't tested this, as I haven't installed version 14 yet.