The new streaming economics are that, unless you are an established multi-billion dollar IP, like Star Trek, Marvel, Lord of the Rings, or Game of Thrones, you aren't going to get enough money together for live-action anything beyond a simple detective show or medical drama.
There's a rare exception now and then - bestselling novel adaptation, established director or writer, etc... Whedon has a bad name right now, so nobody is going to be throwing money at him. His last huge-budget TV show, The Nevers, got pulled from HBO before it was finished airing.