So far these are mostly Asian cars that use CHAdeMO. To our knowledge the following models support bidirectional charging:
The common CCS standard does not yet support feedback but this could change with ISO 15118 and numerous car makers including Audi, Ford, Lucid, Tesla and Volkswagen have made announcements to support bidirectional charging in the future.
It is difficult to predict future regulation. Given that most major car manufacturers have announced plans for bidirectional charging, we do expect wide support for bidirectional charging even without legal requirements.
No, the project aims to maximize self sufficiency through bidirectional charging.
At the moment the market is rather small as only few cars support bidirectional charging. With the required scale we expect the cost of bidirectional chargers to decrease substantially. Nevertheless, a premium compared to unidirectional charger will – most likely – remain.
Additional charging cycles will reduce the lifetime of a battery. The exact impact, however, depends on a whole range of factors as various studies have found (see this for example). Nontheless, we do expect the benefits of bidirectional charging to outweigh the cost of a shortened battery lifetime.