I'm a Trader Between Two Worlds! Helping My Country Max Out Its Tech Tree

[A national favorite + power fantasy + developing the nation through soft tech + lord + wars in another world + revenge without delay] Su Yu: Officer! I have a portal! Officer: Have you been eating too much cheap takeout? Then a silver door appeared out of thin air. The nation is shaken. Have I become a state secret? And the leader of another world, as well as an arms dealer? I trade Longguo’s food and weapons for extraordinary resources from another world. Every deal builds wealth and strength for Longguo. Eagleland: “Oh my God! Why can’t we shake off Longguo’s fighter jets?” Longguo: “Take it up with my PL-15P!” Japan: “Baka! You’re saying Longguo’s people are right over our heads? Then why do I only see clouds when I look up!?” “Marquis Su, where’s my money?” “What’s earned in my territory stays in my territory. Not a penny goes home with you!” “Captain Su, there’s oil in the vampire territory!” “Oil? I can hear the sound of money! Combined-arms battalion, move out!” “Captain Su, the orcs are attacking!” “Second Battalion Commander, bring out my electromagnetic cannon!” From a single person crossing over to armies passing through. From trade between worlds to technological superiority crushing magic. When the Eagleland coalition shows off its strength in our territorial waters, it will witness the wonders of technology from another world. When the natives of the other world still gaze up at their gods, they will witness the iron tide from another world.