If we're talking about desiccants (products to remove moisture from the air), the name brand I've seen the most is Damp Rid.
It's basically a plastic bucket or cup with a basket inside to hold calcium chloride pellets, which are also used in driveway ice melt products (the most effective ice melt product, BTW.)
You can buy refills, or just buy the ice-melt in bulk for a lot less $$. You do have to read labels; some ice-melt products contain a mixture of regular
salt (sodium chloride) and calcium chloride, which won't
work.
I've used Damp Rid and similar products, but there's still condensation on things with a lot of thermal mass like the mains,
fuel tanks, even canned
food and bottles of liquid. These things cool off more slowly than the
hull, and so remain in contact with warmer, moist air longer. So in the long run I haven't found these products very effective for a boat in winter
storage. But I also haven't done any meaningful
research one way or the other, a I'm not in the
PNW where the climate is different.