Also, FTL technology existing would naturally abate the prospects of interstellar war under the Dark Forest theory, because it means FTL communication is possible; and factions that can communicate with each other quickly are far less likely to fight each other. This was, at least in the first book, a (iirc stated) reason why the Dark Forest theory exists.

Of note: It might not require the outrageous levels of technology you might expect to accelerate technology to the delta-v 3I/ATLAS is traveling at, simply because there are absolutely star systems near ours already traveling at a pretty large sun-relative delta-v. We get a ton of galaxy-relative velocity for free from our solar system; we just have to shoot the probe at slower solar systems. Putting (and surviving) biological life in there, however, is a different matter.