> You could use dd, however you'd want a large bs (block size) so that it would output quickly, eg 1024, however the skip attribute (to tell it to start at the location of the squashfs blob) would respect the block size and 2221098 isn’t obviously divisible in anything quickly in my head other than 2…

In GNU coreutils, you can do:

dd if=/dev/zero of=/tmp/z bs=8M conv=skip_bytes skip=2221098

https://www.man7.org/linux/man-pages/man1/dd.1.html

Same with count_bytes. Very useful at times.