> The Russian empire was politically stable throughout the industrial revolution era, and yet lagged behind other great powers substantially.

The Russian empire was (finally) developing industrially at the outbreak of WW1. It's industrialization was retarded by it's hanging onto serfdom (including in practice after it was technically ended) far longer than the rest Europe (that prevented people moving into cities and work in factories).

> There's also a difference between "any country can rapidly develop", and what the USSR did, reaching a superpower status only two countries in the world achieved. For example, the USSR produced 80,000 T-34 medium tanks to the US's 50,000 Sherman tanks and Germany's 8500 PzIV tanks

The US sent over 400,000 trucks and jeeps to Russia (on top of building many more for itself and other allies), built out a massive navy and merchant marine, built 300,000 planes of various types (almost as much as the rest of the other allies and axis combined), supplied massive amounts of food, energy, etc and researched and built the atomic bomb (and didn't steal it). They did this while fighting a war on two fronts and maintaining a relatively good living standard (it's a fair argument to make that they weren't dealing with a direct invasion threat, though). They also had one of the best military supply chains in the world, that still persists to this day.

The superiority of the T-34 is overplayed. It was a decent tank that was good enough to build at scale, but the Sherman was more survivable and just as reliable.

The Soviet Union went to massive amounts of trouble to gloss over lend-lease aid for propaganda reasons. Russian blood absolutely won the war in Europe, but the USSR had massive amounts of help.