Zelensky is talking about accepting neutrality. If this were to happen the Pig or his successor - accepting that Russia doesn't adopt democratic standards - will eventually invade again. Such an agreement would strike me as being the same as NATO membership because the west would come to Ukraine's aid. The only difference would be that NATO troops and weaponry would not be stationed in Ukraine when Russia invaded again.
Of course the devil is in the details and there may be clauses about many things. Knowing that Russia will eventually invade again pretty much makes such an agreement worthless.
If neutrality only means no NATO membership, it doesn't compromise Ukraine's ability to defend itself. It can still arm itself to the teeth against any conventional attack, and it's unlikely that Russia would use nuclear weapons in the next war, if it doesn't do it in this one (the jury's still out on that though).
Russia might demand other concessions though, like not joining EU, or limit the kind of conventional weapons Ukraine can have. Like you said, the devil is in the details. But Ukraine can always reject poison pills like that.
I'm much more concerned about Zelensky's recent statement that Ukraine has to give up some land to avoid WW3. This seems to contradict his other promises about not compromising Ukraine's territorial integrity. If he cuts a deal that gives Mariupol and other cities to Russia, after people died defending those territories, how are Ukrainians going to take it?
