It's a common misconception, but microplastics and forever-chemicals (PFAS) are not the same thing. They're two similar, but distinct pollutants.
> Are saunas and blood donations not also effective for this?
Yes, plasma & blood donations are good at reducing PFAS blood concentration. Some(?) firefighting foam contains PFAS, so they tend to have high blood concentrations. Donations have shown to significantly reduce that: https://pmc.ncbi.nlm.nih.gov/articles/PMC8994130/
> Are saunas and blood donations not also effective for this?
Yes, plasma & blood donations are good at reducing PFAS blood concentration. Some(?) firefighting foam contains PFAS, so they tend to have high blood concentrations. Donations have shown to significantly reduce that: https://pmc.ncbi.nlm.nih.gov/articles/PMC8994130/