Is it possible to change the raspberry pi icons on boot startup

You can easily remove it, adding logo.nologo at the end of the first (and only line in the file /boot/cmdline.txt . About changing it, you need to rebuild the kernel, I'm not sure it's worth it. You can always run a service that displays an image on the boot.
more informations here: https://raspberrypi.stackexchange.com/a/3488
/var/log/boot.log.