@amiloradovsky >the same binary can't work in Linux and *BSD
Obviously the same binary won't work on GNU/Linux and the BSD's, as one is compiled against glibc and the other is compiled against a BSD libc.

The concern about ABI compatibility only applies to proprietary software - with free software, just compiling the source code for each platform is trivial (and even if you can just copy a binary, you should still compile from source).

If your concern is about kernel drivers, I suggest GNU Hurd - as that implements the rump driver interface.


Like GNU, I put GNU/Linux-libre support zeroth and foremost and put support for proprietary OS's like "OpenBSD" as a secondary concern.