[tbrake]

I'm really only interested in weakly solved, i.e. "forced draw from starting position" like the 5x5 variant, not a perfect play tablebase from all possible positions.

Given that 5x5 is (weakly) solved, even though your rough estimates would put its 20-piece 5x5 starting position outside the realm of possibility, I don't think you're discounting accurately how much a reduced board/piece/ruleset can affect those exploding permutations for 6x6 as well.

[Sesse__]

Well, it helps if you can meet-in-the-middle, roughly. And it helps a _lot_ to do a weak solve, i.e., you don't care about winning won positions, only showing a draw with perfect play.