these are great tips! i recently bought some of the buckets (pp), and I've been freezing all my grains and legumes upon purchase for a long time for exactly that reason

i'd be nervous about putting dry ice in a hermetically sealed container like a bucket

a thing i've noticed with storing food in plastic (pet) coke bottles is that they never seem to get beetles and that they tend to collapse a bit over the first year or so; i suspect that, even without a fe/nacl oxygen absorber, the food oxidizes enough to consume the oxygen initially present, which reduces the gas volume about 20 percent and kills any beetles initially present

a lot of my flour is in 6-liter pet water bottles with pp caps; none of it has evident beetles but i did freeze it first

my older notes on the topic are at https://dercuano.github.io/notes/food-storage.html