To boot from eMMC, you will need to change the boot mode settings on the board. You can refer to the last 2 pages of this document: VisionFive2 Quick Start Guide for the details. Debian Image 69 does not support this boot mode.
Currently, I think the U-boot log you had shown previously is from the U-boot in the board’s SPI (SPI bootmode).
Alternatively, in case you would want to boot into eMMC from SPI U-boot, the fstab (/etc/fstab) in eMMC needs to be modified as well, other than extlinux.conf.
Then, you can run this following command in U-boot console to boot into eMMC from the SPI U-boot:
fatload mmc 0:2 a0000000 /boot/uEnv.txt; env import a0000000 200; sysboot mmc 0:2 fat b0000000 /boot/extlinux/extlinux.conf
This is a more ‘hacky-ish’ way of booting into a eMMC rootfs for now, and the next image release should fix the hassle needed 