"Lua" means moon in Portuguese, but although fit wasn't used as a given name until recently.
Luana as a Portuguese name seems to have originated in Brazil, either from the origins mentioned above (including the 1932 movie and possibly the influence of Italian immigrants) and later characters from books and telenovelas, namely
Sétimo Sentido (1982). The association with the word "lua" certainly must have helped popularized the name, but that was probably folk etymology. Its usage in Portugal is more recent, and again by Brazilian influence.
It could also be interpreted as an elaboration of "
Lu" (a diminutive of
Luísa,
Lúcia,
Lurdes) with "-ana" (compare with
Luann our Louanne in English).
Luan seems to be a (Brazilian) masculinization of
Luana.
Sources:
https://super.abril.com.br/sociedade/de-juma-a-luana-14-nomes-que-pais-escolheram-vendo-novela/