Bellingham and his parents famously visited Carrington as talks between the clubs kicked off.
Sky Sports reporter Kaveh Solhekol told the Transfer Talk podcast: "Well look, he was impressed by what he saw at Carrington.
"It's kind of a similar situation to the situation with Jadon Sancho. He hasn't made a decision yet on his future.
"Birmingham have given him permission to talk to clubs and that was what he was doing, obviously before this whole coronavirus crisis.
"But he's a player who is an incredible player, for somebody who's only 16 to have played 32 times in the Championship for Birmingham City.
"He's somebody who's very level-headed, when you speak to him he sounds like he's 26, not 16. He's very humble, he's very well liked by his team-mates at Birmingham.
"Somebody described him to me as having an old head on young shoulders. They also said he's got the potential to be as good as Steven Gerrard.
"His best position is going to be as a box-to-box midfielder. He's a player who's got the world at his feet."