The immigration plan was decided long before Carney.
As far as prefab or anything else, housing prices are a majority land value, taxes, and bureaucracy, it can't make a dent since its not the main issue. Houses don't cost more to build in Canada that in places with cheap housing, its not like laborers are making 300k a year, they can't afford housing either.
Its boring. You open a web browser or Steam, you do a thing, you go to sleep.