Oxides of iron, copper, chromium and aluminum are used as honing compounds. They are all in the range of 0.25 - 0.5 micrometer, nominal particle size. That's a weasel-word for average with some bigger and some smaller particles.
You think that the surface looks shiny becasue the huma eye can't see such fine scratches. But you can with a 8X or 10X loupe.
The problem with a leather strop attached to a hard base is that if too much pressure is applied, the leather compresses under the bevel and rebounds as the end goes by, rounding off the bevel to some useless angle = beginner's mistake.
I need shallow bevel angles for wood carving, gouges at 20, all my knives, straight and crooked, 12 degrees. I can see the leather move if I press too hard.
Leather strops are OK, I have some of those. These days, I like to use 4x6" file cards or cereal box cardboard as a carrier for my chrome green (laced with aluminum oxide, too.) The support can be just about anything reasonably flat. Laminate flooring is good, so is a granite countertop cut off, like the cutout for sinks (free by the dozens). Masking tape is better than any glue. For my crooked knives, 800, 1500 and card on 3/4" aluminum tubing have served me well for many years.