It is at this point beyond dispute that Hamas killed a significant number of civilians on October 7th. The precise ratio of combatant-to-non-combatant casualties is unclear since we know [1, 2] that many of those killed died either in "collateral damage" incidents from IDF fire or possibly the Hannibal Directive. But in any case the fact that Hamas killed civilians cannot seriously be disputed since many videos of atrocities were uploaded online.
However, to my understanding, there is no independent evidence that the Hamas leadership ordered the killing of civilians. That is to say, there is no evidence (to my understanding) that the killing of civilians was a matter of policy. A document released by Hamas indicated that the killing of civilians was not a matter of deliberate policy. Hamas has also previously denied killing civilians.
Indeed, one striking thing is that Israeli officials are much more open in their public comments about targeting Gazan civilians in their military operations, than Hamas leadership was about targeting Israeli civilians on October 7th. This seems to upend the traditional narrative (promoted by e.g., Sam Harris among others) that the Israelis are the moral Western army inadvertently killing civilians while Hamas is an irrational jihadist organization purely bent on killing innocent infidels for fun.
One alternative hypothesis might be that the killing of civilians was indicative of a lack of discipline among Hamas troops, or that the acts against civilians were by a subset of more extremist Hamas fighters rather than indicative of a formal policy. I'm not saying that this hypothesis is correct, but it does not seem to me incongruent with existing evidence.
Another alternative hypothesis might be a good faith misinterpretation of IHL by some Hamas fighters as discussed in the linked question I asked a month ago.
Furthermore, it is not clear to me why extreme atrocities would be in Hamas' interests. Indeed, Hamas' principal aim was presumably to collect a large number of hostages to use as leverage; having the fighters spend hours torturing and pillaging would not optimize for this goal. It also would undermine Hamas' PR strategy, which in recent years has been to portray itself as a relatively moderate organization e.g., the 2017 Hamas charter.
Is there independent evidence that Hamas killed civilians as a matter of policy on October 7th? If not, is it appropriate to ascribe responsibility to the entire Hamas organization for atrocities which were not official war policy?
Note I would like to explicitly exclude any and all testimony from captive Hamas fighters in Israel, due to concerns that such testimonies may have been extracted via torture.