Makes sense, very available. I’ve avoided multi-fuel stoves due to possible hassle when flying with a smelly one.
I checked out the Montbell shops. It looks like the butane cannisters are threaded, neh? Only 230 g
Is denatured alcohol readily available?
I'm sorry I'm really not sure, because I wasn't on the lookout for these other fuels. The only thing I can say definitively is that Japanese gas stations are willing to sell gasoline into bottles, which is not the case in some other places, such as many areas of China.
I always put my stove in checked luggage and no airport ever had a problem with it.