Could I mix flours? Half AP and half00??

I think that would work just fine! A flour designated as Type 00 doesn't indicate anything about it's "strength" or protein content, just the level to which it's milled and sifted (it's the whitest of the white flour). I've made this and focaccia with type 00 many times, turns out awesome 🙂 Just be cautious with the water in the dough, depending on your source for 00, it might not take on very much (but this recipe isn't super high hydro, anyways, just be aware). Let me know how it turns out, I love this simple bread!