Calculation of strip foundation for a bungalow

Is the formwork construction etc. also included in your price for the foundation concrete?

Well, "formwork" here is more appearance than reality :)
For strip foundations, it will be built in a few hours, or let’s say a day.

No, of course it is not included in my stated price of 109 EUR. Those were the pure concrete costs, which have also increased recently. Nevertheless, you are being quoted double the price.
Don’t get me wrong, I’m not trying to badmouth your offer. Maybe the contractor is great and the prices ultimately "justified". I just want to make you aware that it is most likely possible to get it cheaper if one would want to. For that, you have to compare regionally.

You don't need formwork for strip foundations, do you? For me, they just dug holes into the planum.

For strip foundations you don’t need formwork, do you? For me, holes were simply dug into the base layer.

Exactly, hence the phrase "more show than substance." Depending on the execution on site or considering the drainage pipes, etc., formwork might be erected here and there, but by and large it’s just a few boards... or a few more boards.

Formwork missing 5cm clean layer missing Grounding? Base slab? Foil? Whoever forgets something is the cheapest and in the end the most expensive.

We paid 185€/cbm for placing concrete (end of 21), you have to keep in mind that concrete and steel prices have risen so much. These are currently the biggest price drivers in shell construction (not wood).

I find 70cbm quite a lot, roughly 100lfm x 0.6m width x ? depth.

Alternatively, call a concrete plant to ask what they currently charge per cbm of concrete. Then you have a rough idea of what the “material” costs without labor and equipment (concrete pump if applicable).

I was lucky that we could do everything up to the foundation slab in EL, otherwise I would have spent multiple times more.

A tip: get a quote from a landscaping contractor (they are usually cheaper and do the same) :)

With thousands of readers here, there is no one who can help you with your precise question.

The OP’s precise questions (and hints at connections) were already deemed by @ as "not exaggerated" *LOL*