That has to be the reason, right? Why else would Britney Spears pick that specific term for her latest collection of songs? Because as much as I love Britney, I definitely do not think of that Nico song, or a Bond girl, or anyone from a 1950s detective serial.
Then again, the literal translation of “femme fatale” is “deadly woman,” and although Britney is no Jessica Rabbit, she did smash that dude’s car one time with an umbrella. And posed with a snake. And let her kid drive her car. So yeah, maybe she’s on to something there.
(Though here’s a pro-tip: Femme Fatales don’t usually dress like angels.)