GL.iNET Flint 2 (GL-MT6000) discussions

Hey, received mine today and successfully flashes to openwrt 23.05.3 from vendors latest stable web-ui.

After that I had some fun with the plastic clips to open the device to get serial as I wanted to switch to the openwrt-uboot. I installed it successfully through tftp.

Now my question: For me it's uncommon that OpenWRT provides an image with root-fs full-size of the emmc as on sysupgrade the files listed to keep are stored in ram (to my knowledge) and everything is wiped and then rewritten - is that done differently here or should I need to generate my own image with smaller rootfs and make an extra data-partition as usual?