Summary
Oni has pretty good size and athleticism, but hasn't developed his offensive game enough to get consistent rotation minutes. He has only hit 31% of his threes over his first three seasons, and has finished poorly at the rim. He doesn't have a great off-the-dribble game, so he needs to hit shots at a higher rate so he can at least attack hard closeouts in a straight-line drive.

Oni was unable to prove that he belongs in the rotation during his third season in the league, as the Jazz traded him in a salary dump and he was subsequently waived by the Thunder. Oni will already be 25 when he hits free agency in 2022, so time could be running out on his NBA career. He likely can get some training camp offers, but is unlikely to get a fully-guaranteed contract.
 
Cap Considerations
Oni was waived by the Thunder during the '21-'22 season after being traded by the Jazz in a salary dump. Teams will have multiple ways to sign Oni as even teams without cap space could possibly use any of the Non-Taxpayer MLE, Taxpayer MLE, or the Room MLE or Bi-Annual Exception to sign him. It's also likely that Oni only gets minimum offers, and may not even get fully-guaranteed offers.