It is safe to say the HomeKit API seems just as out of date after WWDC21 as it has been for 3+ years now. It is still missing TVs, HomePods, AppleTVs, Airplay2 devices, etc. There was really nothing announced that was actually HomeKit framework related. Home Keys looks like the team that does Wallet. HomeKit Secure Video expansion was just a matter of where and how much video is stored. Nothing related to HomeKit.
The way I read the tea leaves since Apple didn't add anything to HomeKit again this year is this (this is not a real quote just how I interpret the broader direction):
We have spent all of our resources for some years working on CHIP/Matter. We presume that by putting parts of HomeKit into this open source effort, more types and more brands of devices will then become part of it that were previously hesitant to do so. Therefore, we have spent years redirecting our efforts towards that at the expense of essentially everything else.
This seems like a road that will take 3+ years (plus the 3+ years already spent) to come to fruition. Meanwhile, the HomeKit API will still be missing everything that has been announced for the last several years. It's also counter-intuitive as most of the missing devices are Apple devices so they never needed third-party or open source anything to fix that.
Regardless, I think that's what we're getting. At this point, anyone serious about the HomeKit area starting fresh is likely better off using an HAP implementation of their own and basically ignoring the HomeKit API.