I have a Raspberry Pi running Signal K on the computer. This transmits all boat sensor data (depth, wind, GPS, AIS targets, etc) to the tablet. On tablet I can then run a chartplotter app, for example Navionics, SeaPilot, OpenCPN, or my current option, Orca CoPilot.
The tablet does have an LTE modem, but in this case it’s getting internet from the boat (Teltonika RUTX11 modem)