There is nothing much you can do if vehicle does not send the fuel level. Fuel level is probably available from OBD2 if you know the vehicle specific PID request for it. Unfortunately we do not have vehicle specific PID databases.
So should i be looking for fuel level PID information in specific?
If you find the vehicle specific PID for the fuel level, you can customize the OBD2 connection XML file to include that into the PID requests. Instructions here:
RealDash-extras/OBD2 at master · janimm/RealDash-extras (github.com)