Hello Phil,
I remember reading something by a missionary in the Outback. He said redgum wood was the best.
There were a lot of gassifiers (gas producers) in Australia during WW2. I have the impression that most of them used charcoal. Charcoal is usually considered to be a simpler and easier way to get started. https://www.build-a-gasifier.com/powell-gas-producer/
Tone Šuštarič has a gassifier for his tractor that seems to be very effective. See Tractor with gas? thread.