Is Haikyu Complete on Netflix?
No. I don't have Netflix anymore, but I can still remember that only the first 3 seasons are available.
If I remember well, Wakanim has all seasons
Netflix has the first 3 seasons, the 4th is currently simulcast on Wakanim.
All streams:
Animax Plus - Season 1, 2, 3
Netflix - Seasons 1, 2, 3
Wakanim - Seasons 1, 2, 3, 4
1st-3rd Season are on except the 4th. Is not yet fully running at wakanim if I'm not mistaken