You should read Vladislav Zubok’s Collapse. The formal structure of the USSR meant that it was held together by the strength of the CPSU. When the party’s power faltered due to Gorbachev, ambitious politicians took over the SSRs and pushed for greater and greater autonomy in order to maximize their power until they broke the whole thing apart.

China is actually highly decentralized, with individual provinces and localities having a great deal of autonomy in terms of setting economic policy.

They did it all according to Lenin’s formula of “The Right of Nations to Self-Determination Up To And Including Secession”. It was the only country in the world to include that in their constitution.

This isn’t an answer to your question, but with hindsight, we can very clearly see that Lenin was disastrously wrong to structure the Soviet Union in this way. Making a union of formally-independent that was only held together by the political power of the CPSU was a deep weakness at the heart of the project that directly led to the Soviet Union’s breakup. He should have followed Stalin’s recommendation and just had the RSFSR annex the other republics.

Hybrid rice, which has saved millions of people from starvation