i love chaga... & could sense its ancient noble forest spirit from the very first sip...
it is delicious - rich, dark, full-bodied, often compared to coffee, tho perhaps less bitter.
it seems highly unlikely that they could or should be smoked. the outer flesh is rock hard and the inner flesh is of a corky texture - neither seems conducive to pyrolation.
however prolonged boiling (at least 20-30 mins per cup) is recommended... there is speculation that some of the active compounds require extended heat to be drawn into the water. & as mentioned it can be re-boiled several times.
there is possibly a 'doctrine of signatures'-like connection here - the external appearance of chaga is very similar to charred, blackened, burnt wood - suggesting the intense heat necessary to render it fully potent!
i can't find a reference, but i recall reading somewhere that chaga may contain some sort of GABA-modulating compounds? intuitively this feels reasonable as i usually perceive a subtle relaxation & moodlift when drinking chaga.
i don't know about benefits for allergies or asthma, but it certainly has a reputation for being potently anti-carcinogenic/anti-mutagenic, immuno-modulatory, blood-sugar regulating & purifying, & good for the stomach too.
according to wikipedia it stimulates "the production of interferons, which helps induce DNA repair."
and indeed at times i can sense its healing on a cellular and even genetic level.
hooray for chaga! blessings and gratitude!