Cost of construction road / substructure for future entrance

For our construction project, a construction road is generally not necessary, but I have requested an offer from the construction company to still create one, which I can later use as a base for the driveway.

You can find many numbers on the internet regarding what price is realistic there. However, the values differ so much that I would like to hear your opinions/experiences here.

The topsoil should be removed by 20cm and then filled with mineral mixture.
Delivery of the mineral mixture will be provided by the construction company, and the removed soil should remain on the site.

Without wanting to name the price, I would like to have some statements about what price per sqm would be realistic for this.

Digging doesn't cost much. Gravel costs about €13 gross per cubic meter (at 20cm height, so with compaction about 3 square meters). We roughly paid about €15 per square meter for the construction road, but we also replaced 80cm for frost protection. We only need to put the [Sauberkeitsschicht] on top and then lay the stones.