OTA firmwares cannot be restored to. IPSW Downloads collects them for potential future use. They might also be useful if you're doing research.
| ✗ | HomePod (Unknown Model) | audioOS 9.9.13.3.1 (17D6050) | January 28, 2020 | 1.7 GiB | 3133b10d30cc6ddeedcd0bb397ab096988225a42.zip |
| ✗ | HomePod (Unknown Model) | audioOS 9.9.13.3.1 (17D50) | January 28, 2020 | 1.7 GiB | 3133b10d30cc6ddeedcd0bb397ab096988225a42.zip |
| ✗ | HomePod | audioOS 9.9.13.3.1 (17D50) | January 28, 2020 | 1.7 GiB | 23cd55d3361a3df4878ba8a0aec022f1ef6b868e.zip |
| ✗ | HomePod | audioOS 9.9.13.3.1 (17D6050) | January 28, 2020 | 1.7 GiB | 23cd55d3361a3df4878ba8a0aec022f1ef6b868e.zip |