You could do outside, what I did inside. You are on the right path. I would get the concrete patch (available alongside the Dri-dex interior patch in the paint dept) in a plastic tub and trowel it on. Let it dry and paint it. You will need to do the whole wall yourself because it is like a signature. No two people will trowel it on the same. Test it on a concrete block if you need, but you don't, just start troweling and it will fill the cracks and be just fine, you'll see.
It is an amazing look!