I can only speak for Nioh 1 but I thought the difficulty can vary wildly. It's less consistent and less polished in terms of difficulty curve in my opinion but you can also OP yourself with equipment way easier than in Souls games due to the massive amounts of loot. Thing is, the game is a lot more "bite-sized" with some side missions levels being super short so even when you fail horribly it's often not really an epic trek back.
Overall, if you like Souls games in terms of difficulty I'd honestly say you're fine. It's more up-and-down than those games but it's also incredibly addictive and the combat is awesome. Biggest tip I can give you is if you get into Nioh...just do yourself a favor and don't play it like Souls even though it walks and talks like it seemingly at first. Really engage with, and learn, the stance switching, combos and Ki Pulse, it's so much fun and makes you feel like a bad motherfucker once you get the hang of it.
