> a static compiled and linked "hello world" in C on Linux is around ~785KB

Huh?

    $ musl-gcc -xc -static -Wl,-z,norelro -Wl,-z,nosectionheader -Wl,-z,noseparate-code -s - <<eof
    #include <stdio.h>
    int
    main(void) {
            static const char s[] = "Hello, World!\n";
            fwrite(s, (sizeof s)-1, 1, stdout);
    }
    eof
    $ ./a.out
    Hello, World!
    $ ls -l a.out
    -rwxr-xr-x 1 oguz oguz 4976 Jan 12 09:38 a.out

    $ musl-gcc -xc -static -nostdlib -fcf-protection=none -fno-asynchronous-unwind-tables -fomit-frame-pointer -Wl,-z,norelro -Wl,-z,nosectionheader -Wl,-z,noseparate-code -s - -lc <<eof
    #include <unistd.h>
    void
    _start(void) {
            static const char s[] = "Hello, World!\n";
            write(1, s, (sizeof s)-1);
            _exit(0);
    }
    eof
    $ ./a.out
    Hello, World!
    $ ls -l a.out
    -rwxr-xr-x 1 oguz oguz 487 Jan 12 09:58 a.out