Consequences of the coalition agreement for home builders?

no proposal for a technical solution

The whole thing can already be made grid-friendly if the feed-in and consumption behavior of the individual EVs is not left to each one individually, but coordinated at the grid operator level. BMW had a pilot project in California with the i3 (which has been bidirectional from the start, for now over 10 years) where the wall box - controlled by the grid operator - could feed in or draw power. However, the prerequisite for this was that the car is given precise minute-by-minute instructions about when and where it intends to drive, so that the corresponding state of charge (SoC) is provided. Unfortunately, this is quite inflexible for the driver.

can be administered to him without prior warning

Exactly, the idea is about sensible pooling to use electric vehicles for load balancing. Currently, regenerative energy is taken from the grid to keep dirty power plants running at a basic load. Instead of shutting down the wind turbines or dissipating the energy into heat via ground spikes (sounds perverse and it is), a swarm storage system can help reduce the base load of dirty power plants and make better use of the regenerative energy from the already existing wind and solar power plants. The fact that this swarm storage system is mobile, becomes a household item, and is privately financed is only an advantage for quick implementation.
I find that quite logical and good – acknowledging that this is not the solution that should still exist in 30 years, because mobility must also be rethought – acknowledging that there are certainly question marks regarding the sustainability and efficiency of current batteries.

The funding serves to "misuse" greed so that purposeful climate-friendly action becomes established.
Unfortunately, our brain switches off when doing the right thing seems too expensive for us.

Certainly, two people who use their brains can come to different assessments and solutions. Accusing each other of stupidity leads to nothing.

But wouldn't it be more sensible to store the energy that is not currently needed in stationary storage at home?

From a grid perspective, the use of power electronics can lead to quite ugly harmonic oscillations and possibly to damage to the connected systems and outages.