After half a decade of requesting, they have finally added some of these features. However, even if you enable the 'view once' options, the questions will always be viewable unless you manually hide results. So silly! Someone has proposed the idea to add a 'view questions only once' option, but I fear I'll be retired before that happens. So in the meantime, Nursing faculty still can't use Canvas for quiz reviews because we have such a strict rigor and have to protect the NCLEX style questions from being stolen and sold.
Just thought I'd add this little viewpoint for conversation purposes: many faculty think that since students are present in the proctor environment when utilizing the results features it must be secure. However, we've had students provide their MEID to friends and family who were able to print the questions/answers/rationales while the student was in the room. IMO, that is why being able to view the questions, answers, and rationales only once after the attempt is the most secure feature.