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 (17C6054) | December 10, 2019 | 1.7 GiB | f497a2ac27a30fed94c1bda6e68fc6ded0bbba72.zip |
| ✗ | HomePod (Unknown Model) | audioOS 9.9.13.3 (17C54) | December 10, 2019 | 1.7 GiB | f497a2ac27a30fed94c1bda6e68fc6ded0bbba72.zip |
| ✗ | HomePod | audioOS 9.9.13.3 (17C6054) | December 10, 2019 | 1.7 GiB | af01924634c80a9329833656ce1710a17affb31e.zip |
| ✗ | HomePod | audioOS 9.9.13.3 (17C54) | December 10, 2019 | 1.7 GiB | af01924634c80a9329833656ce1710a17affb31e.zip |