Demilitarization of Ukraine, NATO membership and relations with the west in general are all going to be very contentious, and it's hard to see a solution here that both sides will accept.
If what you say is true about Ukraine being willing to trade away Crimea and the eastern territories, then I don't think an agreement is necessarily that far away. Your initial demands in a negotiation are rarely your red lines.
The most contentious point (again, assuming you are correct that Ukraine is willing to cede the above-mentioned territories) will be bloc membership. Zelensky could possibly give some informal guarantee that he has no interest in NATO membership, but having your own foreign policy is a fundamental part of being a sovereign state, so being coerced into promising they will never join this or that bloc is kind of incompatible with Ukrainian statehood. And down the line they will definitely be eyeing EU membership.
Personally I would be sad to see territory ceded to Russia as it would reward their brutal and criminal tactics. I am also highly sceptical of Russia's willingness to abide by its obligations under any peace agreement. However, I appreciate that for Ukrainians especially, ending the bloodshed is the most important thing.
Particularly one next to Russia. (And Ukraine, in particular, after this?!?)
The Chutzpa negotiation approach would of course be, "OK, let's discuss demilitarisation. How and when do you propose to start yours?"
Before the recent escalation of the 8-year war it controlled Crimea and the breakaway “People’s Republics” in Donbas and Luhansk each controlled a small fraction of the territory they claim; before the war Russia and their pawns controlled nothing in Ukraine's claimed and generally internationally recognized borders, that was the proximate problem Russia (which shortly before that time had controlled the Ukrainian government as a puppet) sought to rectify with the war.
Zelensky has said he is open to neutrality, but the problem is that he would need some sort of security guarantees moving forward. Demilitarization of the sort Russia originally envisioned is probably out of the question in any case, so that would solve part of it.
Maybe some solution involving international peacekeepers and demilitarized zones could work. Or escape clauses where Ukraine is permitted to annul their neutrality in the event of future aggression by Russia.
That's what it means on paper. But we already see that in practice NATO is not willing to start WW3 to protect Ukraine.
How is that not clear?
If it comes to preventing the end of the world or protecting Ukraine, NATO has already shown it would rather prevent the end of the world.
That's because NATO hadn't committed to protecting Ukraine.
If it had, Putler wouldn't have dared attack.
Again: How is that not clear?
The motivation to save the world from utter destruction gives greater reason than ever before to not start WW3... at least not over Ukraine.. treaty or no.