Flashing Nerves to CM4's eMMC directly - wrong size partitions?

Hi,

I have:

• Raspberry CM4 8Gb, 32Gb eMMC
• CM4 IO expansion board

I would like to correctly flash CM4 and make it operational (without SD Card).
I was following or lets say combining few sources:

1. https://qbereau.hashnode.dev/flashing-a-nerves-raspberry-image-from-sd-card-to-emmc
2. https://forum.elixirforum.com/t/flashing-a-nerves-rpi-image-from-sd-card-to-emmc/49912
3. https://www.digikey.es/es/maker/projects/how-to-flash-the-raspberry-pi-compute-module-4-cm4-emmc-with-an-os/3e33d2593b914a98bfe7cc08d4af5dbb

I ended up with a working CM4. I can use LAN and connect to it. So it kind of works. But I am confused with the partitioning on CM4. This is the output of cmd("df -h") command on it.

iex(1)> cmd("df -h")
Filesystem                Size      Used Available Use% Mounted on
/dev/root                28.3M     28.3M         0 100% /
devtmpfs                  1.0M         0      1.0M   0% /dev
tmpfs                   770.6M      8.0K    770.5M   0% /tmp
tmpfs                   385.3M      4.0K    385.3M   0% /run
/dev/mmcblk0p1           18.7M     15.5M      3.1M  83% /boot
/dev/mmcblk0p3          510.0M    434.6M     75.4M  85% /root
tmpfs                     1.0M         0      1.0M   0% /sys/fs/cgroup

So this /dev/mmcblk0p3 is to my understanding too small. Am I correct? It should be around 30Gb?

For instance… on my 16Gb SDCard on another Nerves system (plain RPi4 - SDCard, no eMMC) I can see this:

iex(5)> cmd("df -h")
Filesystem                Size      Used Available Use% Mounted on
/dev/root                28.3M     28.3M         0 100% /
devtmpfs                  1.0M         0      1.0M   0% /dev
tmpfs                   368.8M      8.0K    368.8M   0% /tmp
tmpfs                   184.4M      4.0K    184.4M   0% /run
/dev/mmcblk0p1           18.7M     15.5M      3.1M  83% /boot
tmpfs                     1.0M         0      1.0M   0% /sys/fs/cgroup
/dev/mmcblk0p3           14.5G    603.5M     13.9G   4% /root

So, what did I do wrong? I would really appreciate some feedback.
Thanks!

Tomaz