Tunnel Rat - Chapter 357: Engineer Type Techno-Magic Bullshit!

Su Yan adored Xie Yu for many years and finally got what she wanted, but Xie Yu ran away on the wedding day, making her a laughing stock. At that time, Bai Xingfan appeared in front of her. He held a black umbrella in his skeletal hand to shield her from the heavy rain, and the other hand stretched out in front of her with a gentle and determined voice: “Don’t be afraid, still With me.” Su Yan was stunned with tears in her eyes for a long time, and finally, she reached out to Bai Xingfan.

- Description from Novelupdates

After being fired, Lu Qingjiu finally decided to return to his hometown to farm.

At first, he started raising a pig, and then he found that the pig could solve more high-level math questions than he could.

After that, he started raising a flock of chickens, and then he found that his own fighting ability was one-tenth of that of a single chicken.

Finally, Lu Qingjiu finally realised that this old home wasn’t quite right… Especially a certain person by his side who constantly stared at him day in and day out.

Lu Qingjiu: “Are you drooling because of the spicy stir-fry I’m holding or because of me?”

Bai Yuehu pointed at the stir-fry.

Lu Qingjiu: “Then can you let go??”

Bai Yuehu reluctantly glanced at Lu Qingjiu’s arm, before loosening his teeth.

- Description from Novelupdates

I met the male lead in prison.

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.