audioOS 9.9.15.4 (build 19L440) is an official Apple over-the-air update for the HomePod, released on 2022-03-14T17:12:28Z. The update package is 1.24 GB. This is a delta (partial) update that requires 13.4.5 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 60523d3176ec9d1e5643a17c99e03ff8558f1241.zip.