Reading both in context they seem to be saying:
Isaiah: none of the gods of the surrounding nations are real. They can’t do anything. They didn’t exist before Jehovah and they won’t exist in the future either. They will never exist and will never be able to do anything for the people who put their trust in them.
John: God’s Son (his Word) was with him in the beginning when he created the world. God created everything through his Son who is the only direct creation of the Father. God’s Son became flash when he came to earth as Jesus Christ. Jesus represented his Father perfectly by doing the things that pleased him and he declared that his Father is the only true God.
These two texts complement each other in their statements that Jehovah is the only true God and that he sent forth his only begotten Son.
On the meaning of John 1:1 see King and Messiah as Son of God: Divine, Human and Angelic Figures in Biblical and Related Literature (2008) by John J. Collins and Adela Yarbro Collins.