Circuit that tries to do this directly from AC is going to be more or less equivalent to active rectifier followed by traditional SMPS power stage (including so

Circuit that tries to do this directly from AC is going to be more or less equivalent to active rectifier followed by traditional SMPS power stage (including some kind of DC bus with some nontrivial smoothing capacitor). In case when the whole thing is only supposed to work in one direction and input is low fixed frequency AC such construction is simply not worth it.