Chuck Berry, the authorised documentary is being released on Blu-ray and DVD in the USA on November 27th 2020.
https://mvdshop.com/search?type=product&options%5Bprefix%5D=last&q=chuckdoc
You can also download a digital copy on Amazon and iTunes from November 27th.
https://itunes.apple.com/us/movie/chuck-berry-the-king-of-rock-n-roll/id1537012326