How to implement 'set -o pipefail' in a POSIX way - almost done, expert help needed

Question

I have to implement the BASH set -o pipefail option in a POSIX way so that it works on various LINUX/UNIX flavors. To explain a bit, this option enables the user to

Answer 1

The core of your idea should probably involve something like this:

{ cmd1 ; echo $? > status1 ; } | cmd2 && grep -q '^0$' status1 }

In longer form, that would be:

{ cmd1 ; echo $? > status1 ; } |  \
{ cmd2 ; echo $? > status2 ; } |  \
  # ... and so on                 \
  cmdN                         && \
  # ^ note lack of wrapper        \ 
grep -q '^0$' status1 &&          \
grep -q '^0$' status2 &&          \
  # ... and so on, to N-1