Alright, beat the final boss, 77 in-game days and that was taking my sweet time, spending many days at base building up my cult and facilities. I didn't die to any of the main bosses, I've only died once total early on when going back to a completed area where the enemies were much stronger and I was ill prepared.
As with pretty much every game in the genre the end isn't really the end. I will try to go for the plat, already got 72% of the trophies, toughest ones will be beating the main bosses without getting hit, got the one for the 1st boss. Cult really is one of the best releases this year and I've played a whole bunch, highly recommend it.