I ordered the Flojet 18555-000A, Portable RV Waste Pump, 12 Volt DC, Macerator, Includes Carrying Case from AMAZON a few years ago...
I'm pretty sure you can mod this to work like you want. This one has the standard waste tank adapter and uses a 3/4-inch hose for waste output. I have used mine a couple of times to pump from my trailer up through a window and down the house batroom pot.
Normally I use this for filling a plastic waste tank sitting in the back of the truck and then driving to the dump site and emptying the portable waste tank using gravity feed...
I have used a 120V model on a kitchen sink hookup a few times.
I have never looked for an internal tank type macerator type pump...
Marine boat place suppliers probably have a model to use for what you talking about...
Roy Ken
