With Spelljammer, I don't really know how much of it made the transition to 5e. I know there's new material, but WotC's multiverse misses an entire transitive plane, called Phlogiston, to make classic spelljamming work. It's what's outside of the crystal spheres containing planetary systems in 2e. In 5e/BG3, the spheres float in Astral Plane which would essentially make them somebody's thoughts in the old system. With this major change and Nautiloids blipping about as we see in the intro, there is probably little use for a helm on board. In 2e-Spelljammer, Illithids have a speciality called Series Helm that would allow them to power their ships with more than just one person. (The person on the helm usually sacrifices their magical or psionic powers in exchange for being able to mentally control the ship. If you're familiar with Shadowrun, think of a Rigger.) Spelljammer was unfortunately never fully developed. There are loads of missing links and loose ends. Astromundi Cluster has a powerful Illithid faction, but that box was unfortunately designed to be standalone and has it's own origin tale on Mind Flayers.
