It's interesting to see how Apple ended up here. After all, they started the smart assistant concept on a large scale and brought it into the public consciousness. Apple showed us that speech is a serious way of interacting with your digital persona. But they have held on to the APIs and interfaces so tightly that they are losing ground and their user experience is far behind Alexa and Google home.
Right now, there are only a handful of problem domains for which you can develop a Siri App. These are defined by Apple and they don't offer a support system, seriously limiting the ability for developers to be creative and for companies to do interesting things. Siri won't let you order a pizza or use a creative app like the one developed by a CapTecher - it lets your kids ask Alexa what time they can get out of bed without having to wake their parents. That is just one example of the innumerable use cases that Apple does not currently allow.
Even though Apple remains a second-tier player in the Voice and Smart Speaker game, it's not too late. They still have the potential to become a major player. Even though it's losing market share, the fact remains that Siri has the highest number of users and features the widest language support of any smart assistant solution.
Look what happened with the iPhone: it was locked down first but after a year the App Store was launched. Siri, on the other hand, has been closed off to the outside world for nearly seven years. Even with superior hardware Apple needs to open up Siri soon or risk being left completely behind.