>250sqm, 30cm thick brick for load bearing + perimeter walls, 30cm rockwool continuous external insulation, aluminium frame triple pane windows, glazured roof tiles, floor heating + wood stove backup, 15kwp solar panels installation, deep well backup, etc.

Even in Mississippi what you describe would not qualify as a "top of the line house". In fact that would be pretty average working class home.

The kind of homes a lawyer or doctor could afford to buy in low cost area like mississippi can easily be 2 or 3x that size and resemble small castles. Think elevators and wrap around double staircases.