He's 19 has only played a year in top flight, in that time he's got the most assists and goals for his club and is 2nd highest scorer in Belgian league, 3 ahead of Belfodil. Onyekuru plays for a less fancied team, they got to first ever cup semi final as well as overachieving in league.
He's averaged 1 in 2 over short career and 1 in 1 in more recently, that sort of rate is not going to transfer to PL, but it's decent none the less. It's only the Belgian league, but there is some talent in Belgium as national team will attest and we wouldn't discount Tielemans or players at better clubs in Belgium.
I think there's plenty of work to be done with him, but I'd rather have a youngster who has so much in hand they are wasteful and yet still prolific, than a clinical striker who'll get a chance or two a game, much more potential. I think you'd probably try encourage the Theirry Henry development, given his admiration and Henry's progression from wasteful winger to unstoppable force. I'd expect if we did sign him, he's more development than first team, but he has the potential to beat people and be a game changer in short term and that gives him a chance to get a foot into first team and develop into something more, long term.