New construction with a granny flat - heating question and KFW.

Hello house building friends

Since I have a large question thread, I will separate the individual questions after all. It came quite unexpectedly that we got a building plot.

A house construction is planned. New build according to KFW40+ (currently still a question whether KFW55 / 40 or 40+). Using the new KFW subsidy would cover the additional cost 1 to 1.

Now I learned yesterday during the planning that for the new build I will get "2x an air-to-air heat pump heating" installed. Since I can apply for the KFW premium 2x - I need 2 heating systems.
What sense does that make? Well, in the end I will probably get the heating for the accessory dwelling unit cost-neutral.

The house (timber frame prefabricated house) without a basement distributed over 2 levels. 160 sqm main apartment 65 sqm accessory dwelling unit.

Ground floor - main apartment + accessory dwelling unit and the technical room
Upper floor - remaining rooms like children's rooms

The house builder now has a "small and a large air-to-air heat pump" in the technical room.

My plan is rather to switch to an air-to-water heat pump with underfloor heating (should I also install a ventilation system with exhaust air heat recovery at the same time?). But what makes sense for the accessory dwelling unit? Use the air-to-air heat pump of the main apartment and also use underfloor heating there? Here in the forum I often read about the Geisha Panasonic Monoblock. Would that also be something? Questions over questions...
I am really overwhelmed and still at the beginning of organizing all the "topics" for the new build. Since a photovoltaic system is mandatory for new builds - it should then be accordingly large.
Then I would rather take KFW40 without a battery and put modules all over the roof.

I don’t know if the information is sufficient to make a meaningful statement.

Thanks to you

Regards Ben

Addendum:

The house (timber frame prefabricated house) without a basement spread over 2 levels. 160 sqm main apartment 65 sqm additional unit.
The current offer is a Bien-Zenker house - turnkey. However, I would also get the house as a shell and outsource the heating / photovoltaic system / finishing work.

Here in the forum I often read about the Geisha Panasonic Monoblock. Would that be something too?

That is basically a heat pump for DIY enthusiasts. Very inexpensive and good. Assume that Bien-Zenker does not install "something like that." Air-to-air heat pumps are actually intended for passive houses. Very cheap, since no underfloor heating is needed. With two air-to-water heat pumps + underfloor heating, there will be significant surcharges. Especially since then a controlled residential ventilation system would also be added (which is almost standard with the "comfort heating").

Then I have to get an offer for the underfloor heating with air-to-water heat pump so that I can estimate the price. The Geisha just "lying next door."

What would be your recommendation then? And especially regarding the two heating systems?

I think two heating systems are great. No billing issues. Everyone can run their heating according to their own preferences. And the extra cost from 1 to 2 should be reasonable.

P.S. I am currently renovating a two-family house. It will be KFW 55 - each apartment will get a Panasonic Monoblock ;-)
So do it exactly the way you want.

So then 2x an air-water heat pump (Are there advantages to using a split device?) would also be offered by Bien-Zenker (I am currently waiting for the offers) I assume the photovoltaic system that Bien-Zenker offers then supplies both heating systems? It probably isn’t really sufficient. Are there any more opinions or experiences? How have others here solved this? Regards Ben