We have a cheap plastic table and chairs from the reject shop in ours.
I just gave one of our old kids couches (had a sturdy wooden base) to a GF for theirs as it was much larger than ours.
Perhaps instead of a true kitchen what about more of a cabinet/bench of sorts that could be either a kitchen or a shop cash register desk or a work bench with tools...or what ever their imagination chooses? Then you could just have little containers of tools/kitchen stuff/shop stuff/school stuff etc.