How did the axis powers last so long in WW2

Take a look at a map of Europe in 1939 there’s no convenient way for Germany to attack the USSR other than through Poland. Japan was already in China (specifically Manchuria) before the Nazi’s came to power as well.

It would take a diplomatic genius to make all the alliances you’ve suggested (although to give Ribbentrop credit negotiating a non-aggression pact with the Soviets was a pretty sharp move).

More light tanks wouldn’t be particularly helpful, you’d just bounce even more ammo off the USSR’s better tanks (KV-1s and T-34s). The enormous number of soviet light tanks (BT series and over 10,000 T-26s) in 1941 didn’t help them very much in our timeline.

Pre-staging vast amounts of military equipment in other countries is sort of antithetical to conducting a surprise attack.

Leningrad was invested within 3 months of the launch of Barbarossa, yet despite the enormous losses inflicted on the Red Army was never captured. It’s hard to see how an alternate strategy could take it quickly while at the same time focusing on Moscow.

The gauge issue either requires massive infrastructure work to alter tracks or a huge conversion of rolling stock to be able to use wider track - either way it’s a big problem with no obvious solution.

All in all the invasion of the Soviet Union was about as successful as it could possibly be in our timeline, and still wasn’t enough to be complete.