Giraffe hubs?

Is the top hub and sprocket on a giraffe the same as on a bike, meaning interchangable?

it should be.
a friend who is bui,lding a sick giraffe is using trials bike parts.

It’s the same. But there are multiple standards for bikes so you’ll need to go to a bike shop and have them tell you what threading is on the giraffe and what the bottom bracket (middle bracket) shell size is. You’ll also have to get the correct spindle length so the chain alignment is right.

So there’s lots of options. But it’s all regular bike parts. Just a matter of getting the right ones and the right size.