There may be a process for re-acquiring Chinese citizenship but that will require researching the relevant authority. As for going back to being a green card holder, that would require renunciation of US Citizenship and then going through the immigration process all over again.
OP,
The very nature of this process lends itself to paranoia, overthinking, and second guessing. Full disclosure, I was guilty of all 3 and in the end, everything worked out fine.