Microplastics were not a concept created for ideological virtue signaling. I don't know who manipulated you into thinking that was true, but you may wish to re-evaluate where you've been getting your information. The good news is that you don't have to depend on some invented sinister backstory for microplastics, you can instead read the paper where the phrase was coined for yourself (https://www.researchgate.net/publication/8575062_Lost_at_Sea...) and see that it was just a lot of typical boring science like searching through sediment and plankton samples, and keeping track of what lugworms eat. A paper that concludes with "we'd need more research to determine if there are any environmental consequences" is about as far from ideological virtue signaling as it gets. Take your own advice and "Beware those who distort the truth and exploit fear for their own gains."

As far as precision goes, currently microplastics are for plastic bits smaller than 5mm. We even have primary and secondary categories for them. Nanoplastics are for bits smaller than 100 nm. Do we really need a better classification system at this stage? I imagine that shortly after we do, we'll get one. Science loves to come up with boxes to put things in.