The only realistic plan to go to the stars and return within, say, 40 years without using techno-magic is to use lasers [1]. Nukes just cannot do that at all, they are only good for efficient travel within solar system.
The Project Orion people had extensive calculations on how to send a city-sized ship to another star on a ~100 years trip with nukes.
It is laser propulsion that is techno-magic. Even today. I won't register on whatever site to read yet another article on that, but I do bet neither the lasers nor the sail on this one could be made today.
[1] - https://www.academia.edu/1884741/Roundtrip_interstellar_trav...