I am from Brazil and while I never heard of Coco with that meaning, "Cuca" is a very known evil character from a very popular series of children's books called "Sítio do Picapau Amarelo"[1], and I would assume that its heavily influenced by the same legend, while in case of the books she is a witch and based more based on a dragon or an alligator than a bugbear. You can see it here from one of the several TV adaptation. [2]

Also, based on the series there is this popular music "A Cuca te pega", or in a free English translation: "The Cuca catch you". [3]

[1] https://en.m.wikipedia.org/wiki/S%C3%ADtio_do_Picapau_Amarel...

[2] https://youtu.be/bIiujEcXcRw

[3] https://youtu.be/y4YLN0ZQdyk