I don't see how glass, steel, or paper packaging would be superior. Paper is far more carbon intensive to produce (think an order of magnitude), and for food products it must be treated in such a way that it is not perfectly biodegradable wood pulp, but rather lined with plastic or plastic derivatives. It also doesn't work very well for frozen foods.
Glass is extremely carbon intensive to produce, and it weighs an enormous amount meaning a greater carbon footprint to ship products from factory to table. Not to mention it is impractical for goods like freeze dried potatoes mentioned above.
Steel cans and other metal packaging is lighter than glass, but also heavy, and does not lend itself very well to frozen foods, but mainly to preservatives. It is also carbon intensive to produce and lined with plastic. Glass and steel are recyclable, but this is carbon intensive and only works when people are educated enough to recycle and then the infrastructure exists in the first place.
To cap this off, microplastics are not yet even proven to be harmful. The scientific literature is "no" at best, and "inconclusive" at worst. It is not some proven hyper-carcinogen that many laypeople get the impression it is.
I think a lot of people have some sort of pavlovian response to the word plastic done by 25 years of fair and unfair media coverage, without thinking about actual plausible alternatives to it.
"Plastic is bad, we should use X" is an interesting comment worth exploring.
"Plastic is bad" is a statement. Yes, everything in the world has pros and cons, but stating cons in a vacuum isn't insightful.