On an old freedom caravan I had, the pump plugged in from outside. There was a small socket to plug the wiring in and a socket for the water pipe to the pump. The rest of the wiring was permanant inside. however in a dandy, the inside wiring has to allow for the kitchen folding. The outside points were underneath.
The freedom had a foot switch on the floor which was easier than the microswitch in the tap. That would be possible in a dandy, then the only connections inside would be water & waste to the sink.
On my 2005 designer, the waste goes to a recessed connector in the side, so there is a connection inside to the sink and a separate short piece of pipe outside to the container.