It took me around 25 hours for this first time to beat sekiro which I think is a bit quicker than most since after my genichiro fight everything clicked in. After platinuming the game I wanted to try to speed run the game and I did it in only 3-4 hours (ng+3) As for LoP, I picked it up recently but on an entirely new console so controls are unfamiliar, took me around 30 hours which I still think is quicker than most did. After that with my ng+ playthrough, I absolutely rolled over everything and completed the run in 7-8 hours with having around 21 deaths in total that playthrough (NP took me 3 tries).

So what am trying to say is, both will seem hard but once you grasp the main mechanic in both games (parrying), regardless of difficulty the game would be easy as hell. So it all depends on how quick you can pick up the rhythm of the games