Unless you’ve calculated every line to a forced win or draw you don’t actually know the objective evaluation of a position and so you can’t determine “best move”. That’s what a tablebase is.

Yes, I figured that he would need a tablebase anyway. But that's still a few bits per position, the number of possible games doesn't come in to it.

A tablebase does include every possible move from every possible position. There are many transpositions, saving space but still every single possible line from a position is represented in a tablebase. How is that different from every possible game from that position?

A 6-piece tablebase is 150GB. A 7 piece is 18TB. An 8 piece is thought to be 2PB, but we don't have one yet. How big do you think a 32-piece tablebase will be?