There is nothing in the documentation about a tool in the u-boot recovery space that provides conclusive evidence whether the eMMC is gone. Just the reported I/O errors would indicate such, as mentioned by others.
It would seem so
Alternatively the OS can be deployed from:
- interior SSD
- interior USB drive (requires additional adapter)
Running from an exterior USB drive is currently only supported on the Mox platform but not for the Turris or the Omnia.