A feature I'm missing in the Skydemon app, is a feature to plan for a local flight for a given duration rather than a given distance from the airfield.
The duration would simply be something to define at the same time as the radius (Which I assume is necessary for inclusion of NOTAMS and WX ?) , but would give you a compliant fuel planning ref NCO.OP.125 along with a proper weight and balance calculation for both takeoff and landing. Simply using the highest cruise consumption for the purpose would be sufficient.
In EASA part CAT this would be the same as the trip fuel which along with legal reserves give the PIC a better indication of fuel requirement for a given flight.
When measuring the fuel quantity of the airplane, you could easily compare it to your planned fuel in skydemon to ensure you have what is required.