Are you talking about this kind of seatpost?
I don’t know the exact name, but companies call it the “cradle” or “seat clamp”
Enve: https://www.enve.com/product/seatpost-replacement-hardware/
Firefly CNC machines a housing to fit this clamp system:
Thomson: Shop Bike Thomson
There is a relevant discussion about seat toppers here: Seatmast Topper Spec & Discussion
IMO the holy grail design would be a weld-on 3D printed titanium seatpost head that is offset (setback) and uses the Thomson hardware. It won’t be cheap though, probably $80 for the seatpost head print.
Its totally possible, Pinarello 3D prints the clamp hardware on their production bikes.
The Thomson hardware project is on my growing list of things to do.