He reminds me of a little of Sergachev when he started. A little of unsure of his surroundings but you can see the potential.
I can see what you mean in the broad sense of a D that obviously is a little "off" here or there, a little raw in his timing/confidence and that translates to a lesser performance on the ice that will eventually get better and lead to the blossoming of a very good defenseman.
You're 100% right when you talk about the common denominator of a high potential shared between the two.
But aside from that, I actually think Reinbacher and Sergachev are very stylistically different from each other.
Reinbacher relies on good puck placement, quick and simple decisions with the puck, and efficient passing to create counterplay and offense. He does most of his best work offensively with minimal possession time for himself, deferring to his teammates and just quickly connecting plays from defense-to-offense for them, making those around him better while shining a bit less himself offensively.
Whereas Sergachev as a D+2 and even now had/has a much more puck-dominant style based off of his elite-level puck-handling skills for a defenseman, where he can also transition the puck really well with his first pass, but he'll also hold on to the puck much longer and make higher-leverage but riskier plays with the puck on his stick.
Offensively, I'd say Sergachev from his D+2 definitely is the more skilled of the two compared to Reinbacher, with the much heavier and crisper arsenal of shots and better release too. Sergachev's offensive vision from his D+2 year, if I remember correctly, also seemed a little higher-end than Reinbacher's given what I saw of him in his D-1 in the OHL and the little glimpses he showed here and there at camp those two years post-draft.
Defensively I'd say Reinbacher is the smarter of the two, the best of the two at denying zone entries, and the more consistent when it comes to boxing-out opponents, applying pressure on the boards, and defending the high-danger scoring areas of the ice.
So yeah, I understand what you went for in your example but other than a certain common "rawness" to their games, that high upside you spoke of, and the fact that we drafted both with top-10 picks, I don't really see many parallels to be made between Sergachev and Reinbacher if we purely look at their playing styles.