[MauranKilom]

One half-baked idea that came to my mind while watching the bot play on Lichess: You could maybe attempt something similar to how Lichess extracts puzzles. The puzzles generally revolve around sharp positions, so Lichess presumably has some metric for identifying those. They also have some auto-tagging for what kind of situation it is (Fork? Pin? Zugzwang?), although from what I gather these are community-corrected.

That's overall less general than "feed position network output into a transformer", but presumably less data-constrained.