Its a fairly common issue that crops up when you google the symptoms. Ended up doing a logging run and figured out it was hanging in (I forget the official term but the stage where steam installs dependencies into the prefix). And the way to reset that is to clear the download cache in Settings/Downloads.
And yeah, nvidia. But the Warframe shaders are apparently a pretty well known issue. No idea why, but I do know DE are a lot closer to old school iD these days in that a lot of people there enjoy doing fun graphics/engine stuff. Just amuses me that Warframe will take 40 minutes after an update/new proton version whereas Hitman is like 40 seconds.