Onana is a quality goalkeeper and shouldn't be among the offloading list, because he is young with great potentials. I believe that as time passes on, Amorim will help Onana bring out the best in him. Currently, I don't see any goalkeeper in United that will bench Onana who is the first choice of any coach. I believe that soonest we will see the best of Onana.
I always see United fans shit on Onana, but then I watch their matches and I wonder why they always shit on him. He's a very important part of their squad. He wins games for them, by making incredible saves yet, the fans still believe he's the problem at United.
I understand that Onana has some foolish moments and that could be due to lack of concentration and discipline but overall, he's not a bad goalkeeper.
The defense and midfield of Manchester United is not good at all, especially the midfield. They don't have a reliable DM and hardworking and reliable CMs and that is why they can't keep the ball and when they don't keep the ball, the defense and keeper suffers for it.
United need a good midfield, wingers and FBs, but they have no need of a new goalkeeper in my opinion. They can get a second choice goal keeper but Onana is still a good goalkeeper. If they sign even the best goalkeeper in the world, their problems won't be solved.