The folding wing design on the 777X is exceptionally simple.
Compared to the design of some aircraft carrier operated military aircraft or some folding wing motorgliders I do not think so.
There are for example 4 individually actuated latch pins, there is a locking mechanism and there is a folding actuator meaning 6 actuators where most landing gears have only two...
And the folding axis is not perpendicular to the wing centerline, making the structure around it extremely complex. (The alternative would have been more air loads during taxi)
In Boeing aircraft "a conventional environmental control arrangement" puts the system in the wing to body fairings OUTside of the fuselage,
It puts the A/C packs in the fairings, the recirc filters, mixers, fans etc. are all between the cargo bay and the center wing box reducing the available cargo volume.
The dreamlifter is mostly non pressurized, so not applicable.
I was more thinking about aerodynamics and weight. Extending the conventional pressurized 747 upper deck all the way back to the tail would have been relatively easy (they partially did it on the -300 EUD and the -400, they could have streched it even further), but would have created the same issues the A380 has (as you correctly identified): lack of cargo space per passenger and lack of cargo weight capacity.
Not talking area ruling and trassonic drag...