D&D’s new Spelljammer books don’t include a lot of new rules, and that’s OK
The play’s the thing.
“Dungeons & Dragons in space” is a weird idea, and there’s no way to approach it without embracing that weirdness. When the Spelljammer setting was originally written in the late 1980s, it threw together gun-loving hippo people, space hamsters, and a set of interplanetary physics based on 18th century pseudoscience. The end result is a kind of Jules Verne fantasy sci-fi where ships from the Age of Sail take jaunts beyond the atmosphere of their homes and find stranger ports of call beyond.