Otherworld Development Plan

Someone from Earth is reincarnated to an alternate reality that has giant insects and dinosaurs walking around and the inhabitants only has 1910~30s technology.

MC has a “system” that lets him exchange stuff from Earth, due to MC being a 4x strategy fan he accidentally discovered there’s a hidden console command panel.

Suffice to say after that discovery he now can get everything for free! (F-22s, ICBMs, Seawolf class subs, Abraham Tanks, Everything from Earth is FREE!)

Besides that the only other cheat MC has is that he has eternal youth (for realistic story reasons)

Like you can’t expect large world changes things to happen in a short amount of time.

Japan took 100 years to modernise (from the American blackship’s arrival Japan to the start of WW1)
China failed to industrialised which is was part of the reason why it lost to Japan in WW2, and it isn’t until recently that China is considered a developed nation.