Code references in the first developer beta of tvOS 17.4 to "homeOS" could be an indication that Apple is working on a new operating system aimed for use within a person's home.
Apple's Home app icon
The developer betas of Apple's operating systems often include references to unannounced or soon-to-launch products. In an inspection of the latest developer beta for tvOS 17.4, there appears to be some for an unreleased operating system.
References uncovered by MacRumors mention "homeOS," an operating system that appeared in a pair of job advertisements in June 2021 and November 2021. In both cases, homeOS is named alongside iOS, watchOS, and tvOS, before being altered after reports spotted the term's usage.
Outside of the references, there's no indication as to what exactly homeOS will be used for, aside from the name hinting at the environment where it will be probably used.
Apple already operates HomeKit, its smart home framework, which seems like a logical usage for the homeOS name. There's also HomePod, which runs on HomePod Software, a modified form of tvOS, which could potentially get a rebrand with the release of future devices.
There have also been rumors of Apple introducing a HomePod with a seven-inch display, that could be potentially used as a smart home display. Furthermore, there's even been suggestions of an Apple monitor acting as a smart home display when not actively being used with a Mac.
Short of an introduction at an Apple event or during WWDC, it seems unlikely there will be any closure on what homeOS is in the short term.