Secure boot on raspberry pi

Hi Has anyone set up secure boot on Raspberry pi (CM4)? According to https://github.com/raspberrypi/usbboot#secure-boot, a boot.img file needs to be created which contains the kernel, ramdisk, overlays, start.elf fixup.dat, etc files, which is signed and you then program the eeprom to only boot from that signature. There is buildroot here (https://github.com/raspberrypi/buildroot/blob/raspberrypi-signed-boot/README...) which does build the boot.img file, but this will probably not work for opensuse since it uses the kernel and ramdisk, etc from raspberry pi os. Is there any guide for openSUSE on how to build a boot.img file for sue with secure boot on the rpi? Jonas