audioOS 9.9.15.4 (build 19L440) is an official Apple over-the-air update for the HomePod, released on 2022-03-14T17:12:32Z. The update package is 410.25 MB. This is a delta (partial) update that requires 15.3 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: a71bba33ecd5e6f3b04985364edec5c30eded639.zip.