I'm not hopeful when they won't even impose sanctions on Israel, only undeclared "bureaucratic obstacles" at most, not that sanctions are the be all end all of diplomacy, but if anything merited them this would be it. You may counter "oh they have to be neutral so they can negotiate", but I would say to that, what they have publicly said the furthest they are willing to negotiate is a two state solution, which is impossible to achieve. Not to mention the obvious problems with the Gaza strip and the west bank physically being separated and what problems that would entail, the Israelis will never accept a Palestine that gets a seat at the UN, a country that has it's own air space, a country that has it's own rights to nearby oil reserves, a country that has a right to assemble a standing military, a country that could offer a right to return to all of the millions of displaced Palestinian diaspora around the world.

All of these things are a non starter for Israel, there is nothing to negotiate, diplomacy will never compel Israel to entertain a Palestinian state. Unless countries do meaningful things like sanction/divest-from Israel, cut off the supply of weapons, oil, etc. and as long as the US is willing to veto any meaningful UN resolution, nothing will come of any kind of soft pressure, in regards to this offensive or in general. There is nothing to mediate, both the US and Israel have made it clear that Israel will stop when Israel has decided it's in their interest to do so and no time sooner and no amount of arbitration will change that unless more direct meaningful pressure is applied to the state carrying out the genocide.

And meaningful pressure has basically only been applied by states like Iran and groups like the Houthis and Hezbollah no state with any significant leverage over Israel has done anything outside of Iran, including Russia, China, Turkey, etc. who all talk a big game supporting UN resolutions for a ceasefire and making public statements in support of Palestinians, but who refuse to take actions that would actually compel that to happen like divestment/sanctions due to the correct fear that states like the US/UK/etc. would respond in kind with massive sanctions that could hurt economic stability at home.