The possession of a nuclear weapon must be officially confirmed either by Ukrainian government or by a government of a major Western country.
German "newspaper" Bild claims Ukraine might get them within weeks: https://www.kyivpost.com/post/40695
You might want to clarify the resolution criteria for this market. Ukraine has previously had possession of nuclear weapons (see Wikipedia).
Given this historical context, it could be argued that the market should resolve YES immediately. However, I assume the intent is to predict whether Ukraine will possess nuclear weapons again in the future, specifically at some point from now until the end of 2035.
@Benedikt the question is not "will Ukraine have had nuclear weapons by 2035" but "will Ukraine have weapons by 2035", so, at the end of 2035, will Ukraine be in possession of nuclear weapons?