Good question, I think 8...Nd5 is not the most precise. For example, after 8...b6 I think with best play it's hard for White to prove full compensation, as we're able to play with the fact that White cannot play 9.Bd3 there since the g2 pawn is hanging. While after something like 9.Nf3 then we're in time to play 9...Ba6 and we achieve something very important in that we exchange the light-squared bishops. It's true that our knight is left somewhat awkwardly placed on a6 so we have to be precise rerouting that knight (likely back via the starting square of b8). You could also investigate 8...d6 instead when again 9.Nf3 allows 9...Bf5 from us, depriving White's bishop of the ideal d3 square. So White has instead to play something like 9.Ne2 probably, but that's a bit awkward. There's lots of analysis one could do after either of these 8th moves from Black, and I'm away right now without access to my files or a strong engine, but these moves are definitely more principled from Black in my opinion. Hope this has helped.