Kollelman,
thanks for taking your time to collect these references. Let’s now read them together. I think taken together, they are saying that there is potential benefit, but a lot is unclear, and it is surely not enough to use it instead of other protective methods, like vaccine.
A couple of them indeed suggest improvement. Most from 3rd world countries One is non-RCT observing 300 patients very early in pandemic in March-May in FL seemingly without even matching patients to each other by demographics. Most reviews say that the quality is low.
One (already discussed, controversial) study has 15 criteria, of which 1 shows significance moderate, the rest vary between low and very low.