According to Guru Nanak Ji to a peer, "Hell and Heaven is a state of mind. Not a Geographic location."
SGGS states "Jamdoot come and beat up paapis/ Nirguras. Wine and fish eaters go to hell" etc. Also, hell is fire Heaven is freedom, joy, Sukhi saans.
My opinions. Apparently, God is also known as "Upperwale" (Being up there). So if Heaven is up and hell is down (according to tradition) we need to think, what is up? Space, stars! No gravity. Sounds like all the good / religious folks do become stars after death! Of course not the case but what else is up?
Now, lets focus on down... Core of the Earth, Heat! Lava! Hot n scary items. Interestingly we humans may die before getting towards the Earth's core and we cannot reach the nearest star in a single life... (Ok, we should forget about stars). Simply, my opinion is (taking into SGGS account) Hell is Core of the Earth and... IDK where Sachkhand is but must be obviously some place nice. So, core of the Earth is where all the paapi souls are imprisoned n tortured.
According to Guru Nanak Ji live a life where you live life a true hermit. In God's will. By doing so the mind itself becomes like Heaven. Hell and Heaven is a state of mind. Heaven too is, sadly, a Maya (groan) the truest place is with God in His Darbaar.