Code found by MacRumors in the first beta of tvOS 17.4 references a possible new OS from Apple known as homeOS.
I'd say that homeOS is most likely a possible upcoming OS dedicated to Apple's home devices, such as the HomePod and HomePod mini, as well as for managing other smart gadgets in your home. This could make it easier to handle the many apps and services needed to control various smart devices.
It's also possible, given that it isn't called homePodOS, that it may also include the Apple TV, combining tvOS and the current HomePod current into a single unified OS.
Another possibility is that homeOS could be the OS run on the rumoured HomePod mini with a touch-screen.
This isn't the first time homeOS has been mentioned by Apple, as it was listed as part of some job listings back in June 2021, however it was quickly removed after the media found the reference to homeOS.
We may hear more about homeOS at WWDC 2024.