The other angle was discussed in the postwar years — planting a probe on such an object would give our technology a nice boost out of the Solar System in a timeframe we can’t manage with available propulsion.
If we can land on it, then we’ve already boosted to the object’s velocity. Perhaps it would give us a source for raw materials, maybe even rocket fuel.
According to Wiki, some now believe that multiple interstellar objects pass through the Solar System every year. If that’s the case, then we should be able to land on one eventually.