So a bag that’s bigger on the inside but doesn’t link to a pocket dimension. You could also go with the items being shrunken while inside, in that Ant-Man-ish “the space between the particles is reduced, and all mass is retained” way. If the bag breaks, the items revert to normal size.
Bag of Storing, a bag of holding that doesn’t mitigate the weight of the items within.
So a bag that’s bigger on the inside but doesn’t link to a pocket dimension. You could also go with the items being shrunken while inside, in that Ant-Man-ish “the space between the particles is reduced, and all mass is retained” way. If the bag breaks, the items revert to normal size.