Which floor covering is suitable for concrete with cable ducts?

How far apart can the slats be, or what is common? I think if the slats leave gaps of this size, the tongue and groove boards would give way at certain points, right?

We installed tongue and groove boards in the attic, directly on the rafters, which are about 1 m apart. However, with tongue and groove boards, you also have to have the joints directly on the slats. But that can be planned accordingly.

I am now at the hardware store and have described the situation. Since currently tongue and groove boards at 24mm thickness cost about 25 €, and even at 19 mm about 14 euros (which was discouraged), I was offered the following option.
Lay gypsum plasterboards in two layers on the floor, leaving the areas where the cables are free, and then put a cheap laminate floor on top. Gypsum plasterboards cost slightly under 3 euros per sqm, so 6 euros per sqm because double for the required height. The cheap laminate, which we also liked visually, was about 6 euros per sqm. This way, nothing would bend under load, not even with heavy things that one might store (like tiles or so).
What do you think about it?

I am also just an amateur, but I don't think much of that. As far as I know, you can't just use drywall sheets as floor construction. It has to be dry screed, and that is certainly more expensive than 6 EUR /m². Take a look at the relevant classified ads online; builders often offer their tongue-and-groove remnants or sawmills from the region sell directly. You should get tongue-and-groove with >=23mm thickness for around 10 EUR /m². Although personally, I think 19mm should also be enough...

Or use ordinary spruce boards which I have in 5m lengths for 11 euros/sqm. The advantage is also that wood is easier to work with. Underneath each one a roof batten. I would also find plasterboard unsuitable for this.

Or just take ordinary spruce boards, I have them in 5m lengths for 11 euros/sqm. The advantage is also that wood is easier to work with. Each one with a batten underneath. I would also find drywall unsuitable for that

That works too, but then only with shoes on, unless you have soles like Mowgli

That works too, but then only with shoes up there, unless you have soles like Mowgli

Some building owner's soles are suitable for giving these boards a gentle sanding through repeated walking. :D. In our storage room, we also initially wanted to lay OSB, but that is by no means cheaper, then there's unnecessarily adhesive etc. involved, and a board is easier to transport, cut, splice, etc. Besides, I prefer walking on wood anyway.