It's been mentioned quite a number of times in this forum, but there is only one real discussion I know of, in the "similar threads" below:
https://permies.com/t/17045/Rocket-stove-gasifier-biochar
(That's curious, after I posted this comment, the thread no longer appeared in similar threads... is it there after this edit?)
(I used my gardener powers and put several more relevant threads in the "similar threads" section.)
Even that did not go into more technical detail or real-world examples than you just described.