I've done true pacifist and genocide, although I never actually killed Sans. I'm still feeling intense guilt from doing it. I'm waiting for my brother to beat him because I know he doesn't want to go through the whole game just for Sans. After he's done, I will reset and do True Pacifist again, then let Frisk live their life.
As for Snowgrave, I plan on doing it on my third save file, but I'm still playing pacifistly.