kovarex:
Right, after checking again, it really looks like 3 move approach ko, not 2, so I updated the problem. The terminology follows this logic: https://senseis.xmp.net/?ApproachKo The idea is the 0 approach ko is normal ko, 1 move approach ko is, when you (or the opponent) need to do an extra move to start a normal ko, etc.

jhubert:
3 steps kô ? ( not 2 steps)

kovarex:
A16 B18 B17 I have no idea why this could be wrong. As long as I can see black is safely alive after playhing this. It should either be correct variation, or refutation should be added.

Lyde:
I think S2 S3 T3 (lower right) also becomes an advantageous KO, albeit not a step KO

posetcay:
Removed the continuation after opponent B19 because pretty much any move works afterwards (can even tenuki).