The first Dark Souls PC port is notorious for being borderline unplayable with a mouse and keyboard unless you tweak the settings or use plug ins, most just used controllers for ease of use. With later versions of the game, m&k controls seem to have gotten better. Fast forward to today, most PC versions of modern soulslikes allow for both control configurations while still usually suggesting a controller.
Which do you prefer? Have you tried playing with m&k?
Sekiro is a parrying heavy game. To me it’s not souls like, though. The constant bosses were annoying, but after beating Wu Kong, I might give it another shot.