I've been involved in the making of a couple of ukuleles. Don't larf. It's fun!
It's my house mate's thing really and I am on hand with my engineering knowledge and workshop facilities. The acoustic bodies are made from thin sheet and he bought the parts with the sides pre-steamed from a chap not too far from here.
We made a former to hold the sides to size and curvature while kerfings were bonded in along with structural blocks for the neck and bridge ends. The top and back were then bonded to the kerfings.
After his first one he decided to make one "freestyle" from material that was to hand. This was to have a piezo pick-up, pre-amp and tuner built in. His building style is, let's say, casual. He made a biscuit tin shaped cylindrical body from hardboard with slotted ply wrapped around the sides to avoid steaming and setting. The thing weighed as much as a solid body at the end.
Although technically hollow, the acoustic volume is low enough for practice on your own in a quiet room but not much more. Fortunately it sounds flippin' ACE through his amp.
The example you have given where a full cavity is routed out looks like the sides are a LOT thicker proportionately than that above. It won't be loud.
PS: These were all set necks with no truss rod.