have you tried showing them LabVIEW? it ticks tons of boxes:

- graphical

- more advanced (inherently parallel, more useful async data structures like events and queues)

- interfaces with tons of cool hardware

- built in network programming

- pretty powerful debugging

- free with community edition

Once they have the basics down, you could transition them out to a text based language slowly, even using the c/Matlab based text nodes to start