The longstanding system requirements (even the latest) still mention macOS 12.x (Montery) as the latest supported macOS, but that version went unsupported by Apple in September 2024, over a year ago.
However, I was heartened by the release notes for WHD 2026.1 where it says that NextGen WHD is "Not supported for Sonoma, Sequoia, Tahoe flavors due to Next.js 21 incompatibility." So does that mean that non-NextGen WHD does support Sonoma, Sequoia and Tahoe? Or does it mean that we have to wait for NextGen WHD to support those macOS versions to be able to move our WHD server to one of them?