A tactical bishop ending

I've been working through some Bishop endings with my son, and we both found the position in the diagram quite challenging. It is a study by Gorgiev, and it contains a couple of tactical points. I'm not going to give the game away, but a helpful clue is that it isn't just about promoting the pawn.
(An interesting aside. I fed the position into my engine, and it seems to come up with an alternative first move, giving the same evaluation as the solution. I wonder if this study is cooked, or is Stockfish missing something deeper?)