Offbeat indie sci-fi that debuted at Sundance. Two codependent best friends become addicted to the heroin-like touch of an alien narcissist. Critics liked it (88% Tomato Meter), but IMDb voters seem unimpressed (5.7).
Olivia Taylor Dudley stars as Joey, the stressed-out byproduct of foster care and a substantial wine reliance. At her lowest, she’s drinking reds while pretending to work at a coffee shop. At her highest, Joey experiences the euphoria of interspecies intercourse with a celestial being who claims he wants to save Earth. Joey breaks away from her extraterrestrial lover Brian after a night of dangerously passionate sexing, but she finds herself back at his modernistic mansion touching magical crystals with her current bestie Craig. She cannot resist Brian’s healing powers nor his hip-hop dance moves — like an addict going back for another hit.

“so we don’t know how much is Olivia, and how much may be a body double or movie magic.”
much like the X Files poster, I want to believe
FWIW, IMDB doesn’t list any body double or stand-in but they do show an intimacy coordinator.
If Canary ever gets released, there is said to be a great deal of Olivia nude in it. The trailer looks promising.
Based on everything I have read from interviews and the IMDB credits as stated by another poster, I am pretty sure this is all Olivia.
The movie is somewhat low budget and made to be heavily practical so even the idea of them using CGI on her body is unlikely.