BananaPi R3 eMMC overlay resizing

I was curios about the command in the wiki

It suggests:

parted /dev/mmcblk0 -- mkpart f2fs 768MiB -34s resizepart 5 768MiB resizepart 4 67.1M resizepart 3 12.6M 
  # say F to fix gpt global size
reboot

mount /dev/mmcblk0p66 /mnt && umount /dev/mmcblk0p66 && resize.f2fs /dev/mmcblk0p66
  # if resize.f2fs fails, a sysupgrade may fix

Can somebody explain the parted command?
First it makes a new partition of 768MiB? why?
What is -34s?
Why does it resize part 4 and part 3? Because overlay is on part 5 ?

I guess partly my question is why not resize part 5 only, then run the resize.f2fs on overlay to enlarge it?

Thanks,

Okay: I've managed to to this.
Outline:

Installed 23.05-rc3 from sdcard to NOR/NAND and EMMC
Boot production NAND partition, install parted and f2fs-tools

resize /dev/mmcblk0p5 with parted to the size you like
reboot production NAND system, mount and unmount
/dev/mmcblk0p66 as outlined above, then resize.f2fs /dev/mmcblk0p66

I didn't bother with eliminating the free spaces (sectors) between some partitions, as they are minimal.

@panachoi that is exactly what I did myself. Except I built myself an image with the needed tools. I do not like to bother with installing stuff later :smiley:

But the wiki has so much more cumbersome process. I am not sure why they have that. I was wondering if anybody knows if there is a practical reason. I was just curious.