I think Onana would be more us taking advantage of Everton's financial issues and getting him cheaper to make up the squad. He most certainly would not be in our team with Rice and we need someone like FDJ there to play with him. Someone who can move forward with the ball and has superb passing ability but if Rice breaks forward someone who can also fill in when needed. He is ideal for our midfield.
What someone like him does however do is allow us to put out a real shit house midfield if needed, some games when you're under pressure or real crunch away games gives us options. But Onana can play as well, he is technically better than people realise.