Claiming to be a son of God isn’t the same thing as claiming to be God. The distance between these two claims is vast.
In John 9 the Pharisees claimed that God is their Father too. It isn’t a problem to say that and doesn’t imply claiming to be God. Keep in mind the Pharisees were just looking for a reason to stone Jesus so they leveled many false accusations, which he resisted
41You are doing the works of your father.”
“We are not illegitimate children,” they declared. “
Our only Father is God Himself.”
42Jesus said to them, “If God were your Father, you would love Me, for
I have come here from God. I have not come on My own, but He sent Me.
As far as “The Father is in me and I in the Father” goes, it’s just a reference to being in unity with God. Jesus also said his disciples have what he has:
John 14
20On that day you will know that I am in My Father, and
you are in Me, and I am in you.
21Whoever has My commandments and keeps them is the one who loves Me. The one who loves Me will be loved by My Father, and I will love him and reveal Myself to him.”