In my opinion, stretching is not enough and should be accompanied by strengthening of the muscles that get long and weak while staying in bad posture for long periods of time. Doing a ton of rowing, hip extension, abdominal, chin tuck exercises is a good starting point.
For only a minimal set of stretches, my choice would be:
The reverse plank bridge to butterfly stretch is good for correcting rounded shoulders and opening up the groin. Taken from this video.
Couch stretch on a wall to stretch shortened hip flexors.
Standing pike stretch to stretch shortened hamstrings.
Dead hangs for spinal decompression.
Thoracic extension stretch using a bench or a foam roller.
Reverse plank bridge to butterfly stretch is good for correcting rounded shoulders and opening up the groin. Taken from this video.
Couch stretch on a wall to stretch shortened hip flexors.
Standing pike stretch to stretch shortened hamstrings.
Dead hangs for spinal decompression.
Edit: Adding "World's Greatest Stretch"