I agree with both and am undecided if I think it occurred in the home or outside. I agree with OBE that it is mostly unheard of inside the home.
However, when we consider what we are led to believe, that he was on foot, possibly with no vehicle and no home to take her to, it somewhat changes the usual possibilities, if he had nowhere to take her.
This is also not a stranger abduction and it is not unheard of for a relative to molest a child in the home downstairs or down the hall while mom is sleeping, for years sometimes sadly, whether a stepfather, uncle stepbrother, etc. Killing the child at the home, however, may be more unusual.
I as someone else said above, would like to know the layout of the home. Is there an attached garage with a firewall between the garage and home (sound wise) or a finished basement? I would like to know the events the day and night before. I am not victim blaming but were all drinking and celebrating, tired, the child allowed to stay up late due to an event?
He had to carry her one way or the other or walk her or take a vehicle. Leaving the door open does make me wonder if his hands were full. Had he said to her, let's take a walk or go on an adventure and she was walking, there is actually no reason he could not have also taken his skateboard unless he knew he would be carrying her later but then why would you not just dispose of her where you took her to and then take off on your board? However, if his hands were full when he left, because it happened at the home, it may explain the door being left open and the skateboard left behind.
It also was pretty clear from the PC that there was evidence in the home tying him forensically which also lends to it happening there.
I am torn on whether in the house or outside of the home. I also just do not see him walking far in the dark carrying a body. In town or not, with streetlights or yard lights, he still has to navigate in the dark to dispose of her (i hate saying that) and go unnoticed.
Right now I guess I may lean towards in the home although I generally would not in most cases. There is evidence there because something happened there. He had to get rid of her and took her and what he could for evidence, left the door open, left his skateboard and just went to dispose of her and evidence. All videos so far as we know thus far are him seen without her.
All jmo and speculation but I can believe either scenario, inside the home our outside the home at this point.