Fresh plastic, however. Newly made food-grade plastics will 'leak' a lot less microplastics than anything you reuse.

Contaminants/toxins are cumulative, affecting probabilistic negative outcomes. So it always makes sense to do what you can to reduce your exposure.

Your line of thinking here is the same convenient sort of apathy which enables so many to become and/or stay obese.

It depends on what you buy and where.

Not the "entire." Watch some food factory vids. A lot of it is metal, waxed cardboard, silicone etc.