I think there's some leeway for bifurcation, so "guess and check" when there's only two possibilities. It's not as "clean", but from what I gather it's commonplace in competitive sudoku because in some situations it's the fastest way to find the next digit.

But obviously to get to bifurcation you still need to infer enough to narrow a cell down to two choices, so that would still put a limit on solvability.