Bravura seems to require effort, which seems to me to be
antithetical to sprezzatura.

Webster's 1913 Dictionary
bravura
Definition: \Bra*vu"ra\, n. [It., (properly) bravery, spirit, from
bravo. See {Brave}.] (Mus.)
A florid, brilliant style of music, written for effect, to
show the range and flexibility of a singer's voice, or the
technical force and skill of a performer; virtuoso music.

{Aria di bravura}[It.], a florid air demanding brilliant
execution.