i tested CO method and i think there's several considerations be aware of
it should be done outside, but there's cases when death from charcoals happened while coals burned inside. some of them even took place in hotels, probably you need skills for proper coals ignition to do so. using cardboard for this is a bad idea as well as any densely packed combustible material, i tried to ignite coals this way while inside and it gave dense smoke spread on the whole room. alcohol or cooking oil are 'cleanest' ways to ignite charcoals, i tested only oil but i didn't infused in it the coals instead i infused in the oil the paper it burnt long and rather nice.
well on tests i brought coals while they have been ash grey but glowing in the room. the burning zone gives smoke esp when there's lack of air for full oxidation, so i guess some blower at the start may be useful and standing around it is uncomfortable because smoke irritates eyes and lungs, probably you need to stay distant from the hearth or wear some respirator with safety glasses on
i think blower is a very useful device for this and containers w/ vent holes are the most suitable. in my view, the most logical way to ignite and burn coals inside is by infusing them in some flammable liquid and assisting oxidation by blower to avoid smokes, when coals glow and ash grey they give small but irritable smoke so respirator or changing of location may be useful
do SO inside only after you did it outside, because you you should know how much flame it can produce beforehand. otherwise odds are to set oneself in fire. remove any flammable materials proximal to the hearth, etc. put container on flame resistant material but it's basic ofc
also using CO meter at tests is highly advisable, i had rough results of 50ppm per minute. or 3k ppm in an hour. i used small amounts of coals btw and with more quantity results should be better
flame danger is always exist and keeping some water filled containers at hand is highly advisable too, the more the better