Comparison of heating electricity costs for air-to-water heat pumps from different providers

No, as I said, only heating and hot water. Household electricity is already settled.

My comparisons have also shown that a separate meter for the heat pump is not worthwhile.

You can, for example, enter what you pay per year for 7000 kWh household electricity:
in my case €1519 / year.
Or for 3000 kWh household and 4000 heat pump:
€885 + €757 = €1642 / year

Even with 3,000 kWh + 5,000 kWh it doesn't get much better:
together: €1721
separate: €885 + €935 = €1820

Even with a gigantic 7,000 kWh heating electricity (3,000 + 7,000) we have not yet reached the break-even point.
together: €2125
separate: €885 + €1293 = €2178

The meter and installation cost money too. In addition, the heat pump has to be sized larger because of the blackout times.

I find that strange since my heat pump tariff is 5C cheaper and is already positive at 2000 kWh. Otherwise, I already have a small heat pump (5.8 kW maximum output), I wouldn't take less because of the duration for hot water preparation anyway, and I wouldn't need a larger one due to blocking times (at least with my building owner). However, I would definitely recommend (based on the suggestion here in the forum) buying a submeter to know the actual heating/water electricity consumption, and not just "any" number the machine shows (so installation and meter costs should be considered neutral either way).

I'll join in here. We are also still considering whether we should install a separate heat pump electricity meter. Is it true that you need your own meter to use a heat pump tariff? And that the meter also incurs a basic fee? Previously, someone wrote that "Unterstromzähler" are free, so what exactly is that?

Yes, you have to have two and pay two fees - there are apparently providers who handle this a bit differently, but usually it's just not worth it.

The submeter is only for you personally to check how much electricity the heat pump consumes. The difference between the submeter and the main meter is then the household electricity. I regret afterwards that we did not install a submeter right away. At the moment, I can only estimate how much electricity the heating uses, since our heating system does not display the electricity consumption. I am still considering whether to retrofit the submeter. Of course, with this option, you cannot choose a heat pump tariff, but on the other hand, you have the advantage that the heat pump can run when it makes sense and not when the provider dictates it to you.