LDPE becomes soft, pliable and weakened when filled with gasoline.
It dissolves, slowly.
Very easily punctured but not likely to break on impact.
Yes, would make a very good “slow” fuse as the fire melts/releases the gasoline.
With “slow” being relative.
These are not bottles but you get the idea.
www.youtube.com/watch?v=XRjNdgAetQE