There are also objective measures for more fine position evaluation.

For winning/drawn positions: "What is the smallest program that can guarantee your side to win/draw" probably adding some time constraint.

That is a neat variation.

Measuring the size of a model that produces a win?

Theoretically valid, but that's not going to be a very useful/diable.

No, but in practice centipawns reported by the imperfect engine are good.

But I want to point out that in theory there is also something more than pure win/ lose/ draw with prefect play.

I think program size is probably not a good measure since any heuristic you can put in could be discovered at runtime with a metaheuristic that searches for good heuristics. Time and memory make more sense.