Initrd is as useful as it was before. It is just combined with the kernel image. You can still ignore the bits of advice from that blog post, and generate the i

Initrd is as useful as it was before. It is just combined with the kernel image. You can still ignore the bits of advice from that blog post, and generate the initrd using whatever tool that you want, exactly as before. What is added is just one objcopy command to combine the kernel, the initrd, and the command line into one blob (UKI) that you can boot. You can even sign it with your own Secure Boot key, and it will still work, and be more useful than its components, because now your initrd (reminder: built according to whatever method you want) is cryptographically verified.