I Am the Nanny of the Villain - Chapter 4:

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

When he woke up, Chen Xiao, a tech elite business genius, was reborn in a parallel world in 1999, another self standing at the gate of the college entrance examination.

This year……

OICQ was just born, and Goose Factory employees pretended to be girls and chatted with male netizens. Ma Yun was regarded as a liar and was forced to leave Yanjing to start a business in Suzhou and Hangzhou. Li Hong rented two rooms at the Yanjing Hotel and discussed the prototype of whiteness…

This year, Chen Xiao took the black technology guide of the future world, from social software to domestic systems, from domestic chips to artificial intelligence, from new biological energy to DNA remodeling to fight cancer; from quantum technology to anti-gravity engines…

He won the title of “Forbes” and dominated the global media. He suddenly found that he had accidentally changed the world.

- Description from novelbuddy

When 18-year-old Kyle Conner arrives at his aunt's for a summer holiday, he expects relaxation and freedom. Instead, his life is forever altered when he crosses paths with Lilith, the demon of lust and second-most powerful entity in the underworld.Forced into a dark pact, Kyle is transformed into a demon and gifted with a mysterious system that promises immense power. But this newfound strength comes with a deadly price: Kyle must hide his true nature and navigate the treacherous world of demons, all while being hunted by Lucifer and other malevolent forces.As Kyle struggles to control his newfound powers and unravel the secrets of the system, he discovers his ultimate goal: to overthrow Lucifer and bring about a new era of peace. But with the forces of darkness closing in, Kyle must confront the darkness within himself and make impossible choices to survive.Will Kyle be able to master his demonic powers, outwit his enemies, and fulfill his destiny? Or will the weight of his newfound responsibilities consume him, dooming humanity to eternal darkness?

A teenager named Evan Mason was reincarnated into the magical world of Harry Potter and goes to school at Hogwarts!

With only his knowledge of the future and great talent for magic, he takes the path towards the top of the magic world, only to realize that ever step he took, changed everything!