Recessed entrance in a prefabricated house: with or without a floor slab

... it seems to me like tomfoolery.

Can you please explain to me what you mean by that. Thanks in advance.

Well, the support not only carries itself but is supposed to transfer loads. On more or less just a point, it will hardly be able to do that. From my point of view, a mono-pile foundation can only be intended as an insider joke.

Maybe the foundation around the support is supposed to be sufficiently large. As always, one or two pictures (from the plan) here would be more helpful than a thousand words. ;)

I doubt that the floor slab will be executed continuously. Presumably, the floor slab will be insulated on the outside. The insulation layer then also corresponds to the system boundary of the thermal envelope. Therefore, I would actually expect that the floor slab (simplified) consists of the footprint of the house minus the footprint of the house entrance. The house entrance could thus be executed "on site". If the support does not have to bear any structural loads, it can actually be placed on a small floor slab or a point foundation can be executed. It probably remains to be clarified specifically what will happen with the wooden beam during the construction. Presumably, the house manufacturer will want to know from you at what height the support should "end", since it will probably be attached to the ceiling from the ground floor to the upper floor.

Maybe the foundation around the support is supposed to be sufficiently large as well.

But then it almost touches the main base plate and it is silly to lay them individually. In my view, iso baskets along the seam will be the most suitable option. But the provider should have an answer to that – and as known, I would never think of excluding the base plate from the contract volume for money, nice words, or angelic chants. Interfaces have to fit, and there must be ONE person responsible for that.

Maybe the foundation around the support is supposed to be sufficiently large. As always, one or two pictures (from the plan) would be more helpful than a thousand words. ;)

Attached is the picture of how the foundation is planned. I think structurally everything should be fine ;-)

And so we then have different options to plan the entrance and the stairs.