I guess what you need is an organic substance that breaks down quickly enough to be useful but slower than the product it's holding.

Home compostable packaging is already available and is often used for things like bags of coffee beans. These in theory should be able to be expanded to other dry products.

You'd probably be able to get away with similar packaging for things like bread. Has water content but the bread only lasts a few days anyway so it doesn't matter if it starts breaking down in a few weeks.

I reckon much of the technology we need for alternatives exists already, but the cost is currently prohibitive.