I love both these games and recently finished Nioh 2 on PC. First time I have ever heard Nioh described as 'reasonably simple'. Both games are among the most complex I have ever played and have a learning curve steeper even than most flight simulators. Just wilfully complex to the point of absurdity.
Of course, once it all starts to gel that makes them better games. I absolutely love Nioh 2 especially, and for me it's a 10/10 on its own. I wanted to set it on fire and hurl It out a window for the first 20 hours though. Lol.
Playing the first Nioh game at the moment funnily enough, nearing the end of it now. It's very good but very tough. Difficulty wise it's probably on a par with the Souls games, maybe tougher bosses in Nioh, and it also shares many gameplay traits with From Soft's games but with faster paced combat than the Souls games. More similar to Bloodborne and Sekiro in that respect.
Unfortunately owning the PS4 version of the the first game doesn't give you a free upgrade to the PS5 version, but you can do that with the second game. So I'll probably pick up a cheap copy of Nioh 2 on PS4 at some point and then get the free upgrade to the PS5 version.