Don’t know about bright spark you don’t mention how long the bamboo will be? anyway this is how I would do it. As mentioned cut the end of a 20mm rebar at an angle with a grinder to give it a chisel/cutting edge, break through each segment with just the weight of the bar and force. Replace the bar with metal or plastic tube, thread the cable into the tube and withdraw the tube when through.
I’m not going to faff about with cutting teeth. It’d be simpler to have someone weld a hole cutter on a length of steel. I’d only purpose build a long hole saw if I had loads of them to do. Burning it is, more fun too.