Ultimately it's up to Feargus as our studio head. Before OEI was purchased by MS, there was an owner group (Feargus, Darren, Chris Jones, Parker, Avellone) that would decide.

Individual employees can pitch or lobby for certain projects but there isn't a "voting" process. https://twitter.com/0gnjen/status/1354809924631498760

If soft power fails, hard power can also be applied, but that is practically restricted to, "I'm leaving if we don't do this," which is what happened with Pillars. For obvious reasons, this works better for some people than others and is tantamount to a nuclear option.

Pitches/ideas can come from all over, but simply writing and presenting a pitch is no guarantee that it will come to fruition. The Aliens: Crucible pitch was written by Travis Stout. Adam Brennecke pitched Project Eternity and later, with Bobby Null, Grounded.

And the person who pitches will not necessarily be the person who directs. Everything I've directed at Obsidian (other than Deadfire, which didn't have a pitch process that I remember) was pitched by someone else and I adapted it.