Construction costs are currently skyrocketing

Yes, in the floor up to the point where the connection in the wall is supposed to be. From there, it can then be run surface-mounted upwards. Depending on the wall, I would definitely do it surface-mounted there (outside wall or wall to the bedroom).

I am still paying 25 cents for electricity, I'll wait and see how long it takes until that changes .... Until two days ago, you could still conclude a yearly contract at this price here with N Ergie.

I also just did that at the price you mentioned two weeks ago. Both for the heat pump electricity and for the domestic electricity. The contracts start at the beginning of September and beginning of November, respectively.
A buddy talked to an N-Ergie employee about the likely upcoming increase and got the answer that none is currently planned and they expect prices to stabilize or even decrease slightly. An increase would be announced in writing 6 weeks in advance.
Where the price reduction is supposed to come from is unclear to me, but let's see...

We already have the N-Ergie tariff at 25 cents, even though we are still using construction site electricity. I believe I have read several times that construction site electricity "really hits hard." Therefore, I was surprised by the amount and am positive that we will not need the calculated 6,000 euros for construction site electricity and can allocate it elsewhere.

Where the price reduction is supposed to come from is a mystery to me, but we'll see...

To do that, you would need to know validly where the price increase is coming from :) There are various theories to read about. One of them: On the one hand, it is the demand from France because their nuclear reactors are not delivering. This is particularly due to the collapsing cooling options (-> drought). Once the summer is over, this could ease. In addition, gas turbine power plants are running at full speed to meet the demand, which sets the price on the electricity exchange due to the merit order system. It should be clear that generating electricity from gas is currently not cheap. France would also be the key here (falling demand) or political intervention against gas-fired power generation.

I only did that at the price you mentioned the week before last.

Unfortunately, it is only available regionally :(. At that price, I would have reversed my electricity switch...

Unfortunately, it is only available regionally :(. At that price, I would have reversed my electricity switch...

Yes, that is our regional basic supplier. It used to be significantly more expensive than Vattenfall & Co., but currently it is significantly cheaper.