@SteeMan thanks for noticing Just wanted to create a Topic for F3 Air box that's all so the details I kept minimal.
These steps are nothing new, in different threads several times these steps are quoted. The boot.ext is the famous u-boot.ext file indeed.
Earlier we use to have fat partition also shipped in the image file, but now the support for S905X3 is not provided/stopped.
Not sure if in any other Desktop image the fat partition is now included like in old times.
Partition layout of SD card.
Below is the Boot partition files from my SD card, some of these may be irrelevant, to match the file with that of files in /boot use size parameter while renaming,
extlinux.conf file, fix PARTUUID as per the ur disk partition.
KERNEL /Image
FDT /dtb/amlogic/meson-sm1-sei610.dtb
APPEND initrd=/initramfs-linux.img root=PARTUUID=9f9ca195-05 rootflags=data=writeback rw console=ttyAML0,115200n8 console=tty0 no_console_suspend consoleblank=0 fsck.fix=yes fsck.repair=yes net.ifnames=0 quiet splash plymouth.ignore-serial-consoles video=HDMI-A-1:1280x720M@60D