As I said in the other comment, there are already industrial PCs equipped with GPIO, and some models even include an integrated screen

SBCs are good in conditions where reliability is not the primary concern - scenarios where frequent restarts are needed, change sd card, room temperature etc.), but in a boat? I don’t know anything about marine conditions but having a malfunctioning in SD cards and overheating is not uncommon in robotics and especially in drones (where it’s harder to use full fledged PC), few times actually the SD card died midair, no crashes thankfully.