Those sensors just go over I2C. A connector needs to be placed on the PCB. The Leak sensor will just expose the probes.
- Temperature: https://bluerobotics.com/store/sensors-cameras/sensors/celsius-sensor-r1/
- Pressure: https://bluerobotics.com/store/sensors-cameras/sensors/bar-depth-pressure-sensor/
- Leak sensor: https://bluerobotics.com/store/sensors-cameras/leak-sensor/sos-leak-sensor/
Those are also connected to the I2C bus but are on the pcb thus internal.
- Temperature + Humidity: SHT45-AD1B Datasheet
- Pressure Sensor: BMP581 Product Page
- Tank Pressure: ADS1115 Datesheet Note: The tank pressure is an analog signal. Plase design and layout the pcb so that a optional resistor devider could be used but normaly is not used