Design it in such a way so it can be used on boats. Waterproof enclosures, etc.
esp32 are widely used on sailboats.
For reading and displaying engine rpm, temperatures, oil pressure, tank levels.
Battery state of charge and voltages, monitoring solar panels and GPS, IMU for compass. Autopilot motor control. Digital switching of navigation lights, fridges, anchor chain counters
Env sensors: barometer, lighting strikes detectors.
For gateways with CanBus (NMEA 2000), RS 485 (NMEA 0183), Ethernet, WiFi, Bluetooth, Lora, Zigbee. From Mikhail Grushinskiy.