For example I also thought 43.Nb6 Be6 44.a5 Bxb3 45.Bxa6 Ne4+ looked promising because after 46.Kg2 Bd1 seems sufficient to hold the draw (I could list a few variations but they became irrelevant when I found 46.Ke3 instead). White wins easily instead with 46.Ke3 Nxg3 47.Bc8 Bd1 48.a6 b3 49.Na4 (with the deadly threat of Bb7, a7, a8) Be2 (inducing a7 to prevent Bb7 next move) 50.a7 Bf3 51.Bxg4 and black will lose a piece in order to prevent white from queening.
I also looked at 45.Bxa6 Bd1 and believe that to be winning for white after the straightforward 46.Bb7 b3
47.Na4 Ne8 48.a6 Nc7 49.a7 Bf3 50.Bxf3 gxf3 51.Kxf3
I did not spend much time with 45.Bxa6 Be6
Yeah, white Bb7 is the killer in some lines like in your 45...Bd1. That is why i stopped checking 45...Ne4 46.Ke3 Nxg3: I thought the a pawn just marches through after 47.Bb7 Nf5+ 48.Kd3 Nd6 49.a6, but had overlooked our knight can still hold it. Now that I have looked at it again i like 47.Bc8 and your line much better than mine. I'm impressed, actually
-------------
However, looks to me like our opponent now dreams of playing Nc5 and collecting our a pawn. In fact, that is what he'll do in case we just continue to centralize our king. So i suggest to first interfere with Na4-c5 before we continue to improve our king.
I agree with you that allowing Nc5 now (with a move like Ke7) appears fatal. I am looking at 2 lines:
45...Nd7 46.Bf5 Nb8 47.Bxg4 (47.Nc5 Bf3) Nc6
45...Nd7 46.Ke3 Ke7 47.Kd4 Kd6 48.Kc4 Nf6 with the idea of winning g3 now that the white king is far away
The Nf6 idea (to attack g3) came from remembering this quote:
h5 with the plan of 40.Kf2 h4 followed by hxg3+ taking advantage of the fact that f4 is only defended by the pawn on g3. Centralizing our king is important but exchanging a potentially weak pawn now should help us. With this plan the g3 pawn should be easier to attack in the future than h2 is now since our knight can potentially attack g3 from more squares.
I am assuming this quote implied a Nd7 vote since I do not see any other way to prevent Nc5.
So i suggest to first interfere with Na4-c5 before we continue to improve our king.
Nd7: 2 votes (tschukki, LucyLovesCrypto)