My DD was sent up to a grade one class for reading groups when she was in prep. Maybe that's an option?

Also, DD said the same thing, ' when are we going to do proper learning?' But I told her to make the most of it and after a while she was happy to go with the flow. She isn't 'gifted' though just ahead of the others in her class I think she was reading at grade 1 level middle of prep. So your son might need something extra.