hockeyprospect.com had Buium ranked 33rd in 2021, and Wallinder ranked 45h in 2020. They gave Buium a higher mark in everything but skating.
Here are some notes from the 2021 Black Book:
"Buium is an offensive defenseman with exceptional transitional upside"
"What drives his upside that much more is he's one of the more gifted puck movers in this class. His vision combines with his three way mobility and passing skillset. "
"In terms of pure puck skills, Shai is right up there with some of the top defenseman in this class, but he can use them while going at full speed."
Buium and Wallinder are both 6'3"/6"4", very good skaters with upside, but very raw players on draft day.