What varies between Linux distros, for your purposes? Different libc? I would naively assume it’s all just ELF so it shouldn’t be that big a deal to make a portable Linux binary.
That seems separate from swizzling ELF/Mach-O/PE, specializing the binary on first run(!), etc, which is all super cool but something I’d be wary of relying on as a solid platform. Maybe I’m being too cautious, though!
Reading the Cosmopolitan docs, it has some really clever optimizations, and I think I’d be more excited about simply a small and fast libc over the flashier APE parts.