Yes, you can sit up. Getting from prone to sitting is a challenge by yourself.
Biggest problem for me was, you really want to let your ribcage stitch back together and the least strain you put on it by trying to lift with your elbows will pop it apart again. You can feel it.
I settled in to a reclined sitting position, maybe about 45 degrees, and mostly remained like that. Also makes it a lot easier to get up and walk around when you need to.
Have lots of pillows handy. Have one firm, medium size pillow to hug tightly when you cough. Keeps things from popping apart.
I am wondering if a lift chair might be handy ?