Pawn model, preferably in 1:1:1 scale, is needed.

Minimax can be improved by using Unity jobs system. It may require creating additional boards for AI as parallel "sandboxes". It will require choosing which moves should create new board for a thread.

With GetPawnCapturingMoves(GameObject) and GetPawnNoncapturingMoves(GameObject) it should be easy.

Add an option to choose first best move.

Pros:

• removes most unneeded branches with same score
• huge performance improvement for bigger tree depths

Cons:

• removes randomness, CPU moves can be always predicted

Aggresive pruning is when instead of "beta < alpha" there will be "beta <= alpha" and the move will NOT be choosen randomly, only the first one will be optimal.

Integer from e.g. 1 to 5 that corresponds with move tree depth.

Plain colors don't look as pretty as nice textures. Maybe wooden board?

Is it possible for king to land anywhere in the diagonal after capture? And also can I use this on my game commercially?

Delete renderers and click detectors, create new interface-based components. Accidental click causes null pointer exceptions. Crowns cause strong performance drops.