ᐅ Centralized ventilation system ductwork entirely routed through the attic?

Hello everyone, I joined this forum because we are planning to build a bungalow. Currently, two questions remain open: besides the heat supply (we are currently leaning towards a ground-source heat pump with earth collectors or a ring trench), it’s the ventilation system. At first, we considered a decentralized system since we ventilate a lot anyway and thought of it as an add-on. After researching the topic more thoroughly, however, we realized that you probably can’t ventilate as much or as controlled with such a system, and a continuously running decentralized ventilation might be disturbing due to noise.

So here is my question: We are planning a bungalow with a wooden intermediate ceiling, insulation in the ceiling, and an unfinished attic. We want to use parts of the attic for storage, for example for Christmas items and the like. Before I start deeper discussions with the installer, I would like to know whether loosely laying the ducts in the attic and leading them through the suspended ceiling would make sense? This would have the advantage that we could easily access the ducts at any time, which gives us some peace of mind. Another general contractor suggested embedding the ducts in the screed, but with the now contracted companies, we have not spoken in detail yet, except for the general contractor.

Thanks for your advice!