Really impressed with your theories! Many of them sound super plausible and I enjoyed reading through them all. I agree with the other poster that it certainly is an allegory about our corporate culture, and the only thing that makes me really think Playdead feels that way is the utter lack of marketing for this game.
The fact that they are based in Denmark makes a lot of sense with that message, as advertising is largely restricted in Denmark and the culture there is very centered around keeping a low profile and having a good work life balance. So perhaps this is a very dark allegory of the "Nordic Theory of Everything" as it were, which consists of studies and research on why people in Nordic countries are happier on average. Also playing into that, there are only white people in this game, which I'm not saying as an "oh no lack of diversity!" but as a further reflection of the culture and environment that the studio comes out of.