“On the other hand we hand the Gospel and Letters of John that tell us that not everything is in the Bible.”
Of course we don’t have everything in the Bible. We have what God chose to inspire. What He gave us is authoritative, sufficient and complete.
Everything else - which none of us know - is comprised of everything He chose not to inspire and include.
Everything else - which none of us know - is comprised of everything He chose not to inspire and include.
So all that is stuff we don't NEED to know.
He didn't tell us that he included all knowledge of everything in the Bible. He did tell us that we have everything we need for life and godliness.