I too would like an OS where called programs don't need to call open() on strings. The shell already has <input >output redirection, but hamstrung so few ever use them. So many programs recreate the functionality with -i -o in some manner to make up for the flaws (read multiple inputs, avoid creating a file on error). Graphical programs could request a fd from a trusted file picker instead of requesting a string to call open() immediately after. That just scratches the surface, so much security and convenience to gain.