You are right, the emmc is not detected on the contrary to a previous build I already installed on it (that's why I don't check that...).
Result of lsblck:
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
mmcblk0 179:0 0 59,5G 0 disk
└─mmcblk0p1 179:1 0 58,9G 0 part /
zram0 252:0 0 50M 0 disk /var/log
zram1 252:1 0 1000,8M 0 disk [SWAP]
And dmesg is here: