To add to herecomesthe sun on masks...
I've not read the research myself, Ted - my degrees aren't in the right area to understand it sufficiently fully - but, as such, you'll forgive me if I defer to the conclusions of CDC, PHE, HSE, WHO etc. over your post. The following are the results of a few minutes googling.
www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/diy-cloth-face-coverings.html
www.england.nhs.uk/south/wp-content/uploads/sites/6/2020/09/4A-COVID_Info_Sheet_Masks_and_Face_Coverings_V1.0.pdf
www.hse.gov.uk/coronavirus/ppe-face-masks/face-coverings-and-face-masks.htm
www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks
www.bmj.com/content/369/bmj.m1435
It's worth mentioning that, yes, you will find among the published evidence on masks observations that the degree to which they mitigate transmission is unclear and different types offer different levels of protection. This is, as I understand it, because it's extremely difficult to carry out a controlled scientific assessment of mask efficacy. If you think about this, it's easy to see why! Our understanding is therefore far more nuanced than that, and also continually evolving (hence the shift from early guidance against mask-wearing into more universal agreement in its favour). This has led to a lot of people without an understanding of this complex process, or with an ulterior ideological bias, jumping on the "masks don't work" bandwagon.
The following link is a relatively early BMJ metastudy which reflects this; the opening 2 paragraphs of it explain things very nicely, and the ethical "precautionary principle" to which they refer essentially sums up what I believe still now. Published in 2020, however, it's now out-of-date, and superceded by the more conclusive evidence posted by herecomesthesun above. Nontheless, I paste their conclusion below:
"In conclusion, in the face of a pandemic the search for perfect evidence may be the enemy of good policy. As with parachutes for jumping out of aeroplanes,38 it is time to act without waiting for randomised controlled trial evidence.39 A recently posted preprint of a systematic review came to the same conclusion.40 Masks are simple, cheap, and potentially effective. We believe that, worn both in the home (particularly by the person showing symptoms) and also outside the home in situations where meeting others is likely (for example, shopping, public transport), they could have a substantial impact on transmission with a relatively small impact on social and economic life."