The solution to this type of intentionally incompatible product is to return to a legal and cultural environment that respects adversarial interoperability[1]. If a company doesn't want to implement the features people want[2], some other company should be able to provide their own (possibly reverse engineered) implementation.
Trying to restrict competitors from making interoperable products is admitting you don't want to participate in a well-running competitive market and instead deserve monopoly power.
It was kind of a brilliant move by Shimano, in retrospect. Since Shimano did share with them how to do everything, it makes it much harder to now go and implement those features after the contract has been invalidated.
Seems like a good time for SRAM to realize they should open up info on how to let others create apps for the Hammerhead devices to let indy devs figure out how to reverse engineer Shimano's system.
Trying to restrict competitors from making interoperable products is admitting you don't want to participate in a well-running competitive market and instead deserve monopoly power.
[1] https://www.eff.org/deeplinks/2019/10/adversarial-interopera...
[2] including features like interoperability with a competitor's product.