audioOS 9.9.15.2 (build 19K52) is an official Apple over-the-air update for the HomePod, released on 2021-12-13T18:28:22Z. The update package is 310.26 MB. This is a delta (partial) update that requires 15.1.1 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: f6f3f1deab17948cea9d277547a14601a308d486.zip.