OpenWRT Small Disk Partitions

Haven’t found any help with OpenWRT forum, so wanted to ask here.

Have a new Turris Omnia, I have installed OpenWRT following the “Installation with U-Boot 2019.07 or later” guide here [OpenWrt Wiki] Turris CZ.NIC Omnia.

With the Turris Omnia OEM install the root partition uses the 8GB of the MMC. With the OpenWRT install the root partition is only using 100MB of an overlayfs. See screenshot below.

How can I get OpenWRT to use the 8GB of the MMC? Thanks.

You should ask on OpenWRT forum as when you install pure OpenWRT you loose support with Turris