"Low" is an adverb describing a lack of altitude, literally or metaphorically, with a broad variety of application: lowdown, low spirits, low condition, low temperature, low comedy, low notes. Use any and all such applications freely.
But please, do not ask "low" to stand in for the interjection, "Lo!" meaning something akin to "There it was!" only more sudden, as in "And lo! the Angel of the Lord came upon them." It wouldn't be nearly as impressive if low, the Angel of the Lord started talking out of gopher holes.
Nor does it make any sense to speak of "Low and behold." You wouldn't say "bee-hold" as if you were coddling insects. Just because it sounds the same doesn't mean it is the same.