I agree that this is a far-off idea and yet it has generated some thoughts expressed here. Mankind will travel the stars unless we destroy ourselves first.
You asked how we are going to slow down to near zero and I say we do not have to. Everything in outer space is in motion. All we must do is match that speed of the nearby object and once done we are at zero relative to the other object.
I agree that using the pull of gravity of a far off galaxy is nothing less than farfetched but we do need to start thinking out of the box if we are ever going to get to where we want to go.
Inventions do not come by chance. Someone got an idea that was far-fetched and turned it into a reality.
Science fiction is a genre of speculative fiction that typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel universes, and extraterrestrial life. Wikipedia
Fiction generally is a narrative form, in any medium, consisting of people, events, or places that are imaginary—in other words, not based strictly on history or fact. In its most narrow usage, fiction refers to written narratives in prose and often specifically novels, though also novellas and short stories. Wikipedia
At 70 with little to nothing to do I come up with wild ideas and express them on talk boards like this one. My doctor told me that this is a healthy thing to do so I do it.
There is no conclusion or end product to this discussion, it is just a way to express one’s thoughts.
It’s been fun for as long as it lasted.