How about no initramfs? The Kernel can even boot from encrypted raid volumes as EFISTUB or even more complicated setups without any further need for user space software.
On non-critical devices which can be booted via USB in a case of emergency (like laptops or desktops) initramfss are kind of pointless and just unnecessarily prolong the boot time.
As long as you statically compile in the ext4 (or whatever FS) support every needed kernel module can then be loaded regular boot.