These are about twenty years old (Linux 2.2 and FreeBSD 3). While they almost certainly still work on modern hardware thanks to the backwards compatibility of the PC platform, can it be done with newer software?
OpenWrt run's on 4mb flash / 32mb memory devices. If you disable IPv6 / Wireless drivers and tune some more knobs you get probably something that boots a recent 4.14 kernel / musl / busybox from a 3mb squashfs and runs in 16mb memory.
Strongly trimmed linux kernel + minimal userspace based on klibc will certainly fit on 1.44MB. The dash (x86) built with klibc occupies something with <50kB in memory, below 100kB on disk.
That 5MB figure doesn't include the kernel. Usually when people refer to Alpine being only 5MB they're talking about running it inside of a container/chroot.
