@Buba asked right question - when in 41? before,or after german backstabbed their ally? and remember,that soviet planned to attack germans,too.
Only difference - bulk of sralin armies were on Ukraine,so they would go to 1991.When bulk of german armies was on Belaruss.
Soviets in 1941 are crippled,germans - not so.
About flying nukes - if they have codes,they could use it.But,i read,that codes were still in Moscov.
If that was true,Ukraie could not use them.
So,we have 2 scenarios:
1.They use nukes and wipe out Berlin and few other german cities.Hitler HQ in Prussia,too.End of war,and then what? they would not agree to serve Sralin.
Most likely - they become European superpower,becouse sralin would widraw from his conqests.
2.They could not use nukes - but,still stop germans,and ,as more reliable ally then sralin,get Lend- Lease instead.
In long turn,the some oucome.Themwhat would happen in 1991? soviets on Ukraine would have armies prepered to attack germans.
What would they do? and what other countries would do? invade soviet Ukraine ?