Many thanks to betty for the news and links!
Music documentary, Dogstar Siriusly Singing Backup, is in post-production as of January 3, 2018 according to IMDb. The documentary is directed by Jes and Wilson Stiner. The synopsis is below.
Nineties band Dogstar struggles to keep attention on their music despite the world’s obsession with their celebrity bass player, Keanu Reeves.
The Stiner Brothers have a directors reel posted on vimeo. The first 47 sec includes a segment with Keanu and Rob Mailhouse talking about Dogstar.