Were the signs Moses performed before Pharaoh mainly for Pharaoh or for Moses and Aaron?
The signs were mainly for Moses and Aaron, not for Pharaoh. God used them to prove to those two men that He would supernaturally bring Israel out of Egypt. Pharaoh was not the primary beneficiary; the miracles confirmed to Moses and Aaron that God was truly in the mission.
Les teaches that when Moses objected that Pharaoh would not believe him, God told Moses and Aaron to throw down the rod so it became a serpent. Les explains that all these signs were not so much for Pharaoh's benefit but for Moses and Aaron, to prove to those two men that God was going to do the supernatural and bring Israel out of Egypt. This fits Israel's long demand for signs, seen later in Christ's earthly ministry and miracles to prove to the Jew who He was.