Many guns with frame mounted lever type decockers work exactly like the MK23. SIGs, Walther P5, HK P9S, CZ99. Essentially, they don't just release the sear but control the hammer as long as you keep pressure on the lever. (To be precise, the P9S doesn't even release the sear but just controls the hammer.)
Frame mounted sear trip type decockers release the sear and let the hammer fall with full force into a hammer intercept. Slide mounted decockers trip the sear and retract the firing pin instead of intercepting the hammer.
You can safely decock any hammer fired gun silently by restraining the hammer before pushing and holding the decocker down and then lowering the hammer slowly. But it generally takes two hands.