You could, for example, have a defensive Italian faction built around German support, and so they could have a non-doctrinal FlaK 88 or Tiger at T4. By having access to both Italian and German doctrinal stuff you could design a stronger, more unique faction without having to re-use Ostheer and OkW stuff.
I would be on board with this, but rather than call it the Italian faction just call it "North Africa Army" which featured combined italian and german forces.