We use the bags like this from Amazon: https://www.amazon.com/Natural-Purifying-Deodorizer-Eliminator-Non-Toxic/dp/B071YLSWHW/ref=asc_df_B071YLSWHW/

There are lots of similar choices

For maintaining the dryness/freshness after the boots have been dried out, they are good. Not enough to dry out boots by themselves.

This is the boot dryer we have: https://www.amazon.com/gp/product/B07FT8KRBM

Charcoal Shoe Inserts (Amazon) They work like a charm, inexpensive and help heed off odors too.