What ideas would be most worthy to share in a literary discussion about The Giver Chapters 22-23?

At the end of the book, we are not sure what happened to Jonas and Gabe.  A literary discussion could look at the textual evidence to support what you think happened.

This book has an ambiguous ending.  That means that we do not really get a clear answer about what the ending means.  There are two ways you can interpret it, at least.  On the one hand, it might seem that Jonas and Gabe survived their journey and were rescued when Jonas came to a house in Elsewhere.  On the other hand, you could interpret the ending as Jonas’s death, with Elsewhere representing death or Heaven.

In support of the first ending is the fact that Jonas has maintained his strength through the memories, which would have held him longer than an ordinary person.  That is the novel’s science fiction bent.  You could say that there must be communities other than Jonas’s that do not necessarily subscribe to Sameness. Otherwise, why would the community try to keep everyone there?

Consider the sled as evidence that Jonas is really alive.

Using his final strength, and a special knowledge that was deep inside him, Jonas found the sled that was waiting for them at the top of the hill. Numbly his hands fumbled for the rope.  (Ch. 23) 

When Jonas finds the sled, he knows what it is from the memories.  This does not have to be a coincidence.  During his training, Jonas experienced hundreds or thousands of memories. He probably has a reference point for everything or almost everything he might encounter.

However, there also does seem to be evidence to support the fact that the sled is just an illusion that Jonas is experiencing in his starvation and hypothermia.  Did he travel far enough?  Would there really be some communities with Sameness and some without?  These do seem to stretch the suspension of disbelief.

Jonas describes himself as losing consciousness as he goes on the sled, and then he hears people singing.  This might have been just wishful thinking.  Even Jonas does not seem sure that what he hears is real.

Behind him, across vast distances of space and time, from the place he had left, he thought he heard music too. But perhaps it was only an echo. (Ch. 23) 

The ending you choose depends on your reading of the rest of the book and your interpretation of these events. Of course, if your teacher allows it you could also mention that there are three loose sequels.  That would seem to support Jonas and Gabe’s survival.