>

Also Russia had the codes these nukes were not usable for Ukraine.
What value does a treaty with Russia have? >

The Ukraine invasion is a massive violation of the Budapest Memorandum, so zero. >

The Budapest Memorandum isn't/wasn't a treaty, it was basically a 'gentleman's agreement' which Ukraine agreed to because NATO and CIS were doing the national equivalent of wandering around Ukraine going "wow, gosh, this place sure is inflammable.  You better hand those nukes over to us or this whole regime might just go up in flames."  They received no real guarantees or assurances in exchange except the signatories 'super double pinky swearing' to not invade them.
Russia has violated a lot of treaties, though.  The Intermediate Nuclear Forces treaty, Open Skies treaty, the Chemical Weapons Convention, and IIRC they've recently begun to renege on their commitments to the new START treaty (although I could be wrong on that one.)