I think reason why slitting one's wrist is not considered viable by many is becuz it's too slow and painful. and that survival instinct kicks in.
not pro-lifer but bear with me on this one. I have CPTSD and OSDD thanks to my fucking childhood. diagnosed. and it's not like the trauma stopped once we went out-of-state for college. I been r*ped, and medically abused (as with almost all actively suicidal people). I (think I) get where you're coming from. the way I see it, we seek out more trauma cuz that's what we know best. I desperately want to be harmed. badly. I ask to be hit, strangulated, abused. damn, I mean, my roomies were all balling their eyes out when I struggled to finally say "hit me, hard. please." I'm shoulder deep in pain but utterly needs more. I wanna be punished cuz I should. that's all I deserve to have.
that is a huge sign for complex PTSD. not pathologising it in any way. just acknowledging that it exists.
so I'm not exactly sure if your goal is to die or to self harm. maybe both. you can go with just SH, or take your SH method to an extreme such that you end up dead. even though I'm not too certain if it'll work out.