There are some boxes out there with a internal NAND storage instead of eMMC. These aren’t supported.
Also there are some boxes out there with an encrypted bootloader what will prevent you for the usage of BL301.
I don’t remember this two devies anymore but I am sure you will find it on the forum.
In general are only devices supported by ceemmc if we tested it by ourself on the hardware. But you can rsearch the forum about other user experience.