In this Sunday's Washington Post, columnist David von Drehle suggests that a way out of the difficult Russia/Ukraine situation would be for Ukraine to become like what happened with Austria in 1955 and since; it formally became officially neutral, not joining either NATO or the Warsaw Pact, and has remained so since. For Ukraine this would in effect grant Putin his demand that Ukraine not join NATO, although it would not involve pulling NATO back from such nations as Poland the Baltic states as he has also demanded.
It is easily forgotten that for ten years after WW II Austria was like Germany was iniitially: chopped into four zones of control, one of those in the east being Soviet, which included Vienna, but with Vienna, like Berlin, also chopped into four zones of control. In Germany, of course, at the end of the 40s the three parts of Germany plus those of Berlin controlled by US, UK, and France, combined to form German Federal Republic, aka West Germany, with the remnant Soviet parts becoming the German Democratic Republic, aka East Germany. Such an outcome did not happen in Austria, where the parts all remained separate until Austria was unified in 1955 with the agreement it would become a neutral state.
Many today only know of this period after the war if they see Carol Reed's film based on Graham Greene's novel from 1949, The Third Man, with Orson Welles in it, a great film for sure. I remember visiting Vienna in 1958 and seeing lots of war damaged buildings then, since rebuilt.
That all sounds nice. There is a problem, however. In 1955 the Soviet Union had not annexed a portion of Austria, and it agreed to let the part of Austria it controlled become a part of this newly neutral Austria. As it is today, Russia has invaded Ukraine twice, annexing one portion of it, Crimea, an act still unrecognized by practically any other nation, although Belarus's Lukashenka seems to be now referring to it as a done deal, if not officially so. And then we have the Russian-supported Donbass republics, also unrecognized as independent by anybody, not even Russia itself so far.
So, to have any sort of equivalence to Austria, Russia would have to undo its annexation of Crimea and return it to Ukrainian control as well as withdraw support for the Luhansk and Donetsk republics. Neither of these seems to be ready for proposal by Putin, especially the Crimean annexation, which was and remains popular in Russia, even if an invasion of Ukraine now looks not to be too popular. And indeed, many think the diplomatic outcome he might accept is not withdrawing, but in fact regularizing and gaining acceptance of the status of the separatist republics.
An Austrian outcome might well be the best possible one around, but as of now it does not look like Putin is about to offer anything that would look like what the former Soviet Union offered in 1955 in th case of Austria. This looks like mostly nice talk, but not a likely outcome.
Addendum: Prior to WW I Austria was the core of the Austro-Hungarian Empire. After the war it became an independent republic with roughly its current borders. in 1938 Hitler made it part of Germany with the Anschluss. Thus at the end of WW II it was separated from Germany and chopped up into those parts as was Germany. This is what presaged the 1955 deal that put it back together as an officially neutral state.
From the beginning of the UN, not only was the USSR a member of it, but also two of its parts, the Ukrainian SSR and the Byelorussian SSR, a deal Stalin cut when the organization was formed, although only the USSR held the Security Council seat, those two were only in the General Assembly. When USSR broke up, Russia inherited the USSR's Security Council seat.
There are three agreements regarding how Russia should deal with Ukraine, although two of those were signed by the USSR, not Russia per se. The first of those is indeed the UN Charter, with any member of the organization supposed to respect the sovereignty and territorial integrity of fellow members, with Ukraine actually such a member from 1945 on. Of course this is an agreement Russia did not sign itself, but supposedly is supposed to follow UN rules.
Austria would join the UN in 1955 and agreeing not to join NATO. In 1975, the USSR would sign the Helsinki Accords, which allow nations to join whatever organization they wish to. It is this agreement that is why NATO nations refuse to allow Russia to forbid Ukraine from joining NATO. However, as Austria and Finland have chosen not to, so Ukraine could choose to promise not to, if it were given sufficient motivation to do so by Russia.
Finally, there is the Budapest Accord of 1994, signed by US, UK, Russia, and Ukraine, when the latter gave up its roughly 2000 nuclear weapons. In that one Russia itself promised to respect the sovereignty and territorial integrity of Ukraine.