We use high alkaline cleaner and some diamond impregnated brushes.
There isn't much happening there besides the soiling so you needn't start to low maybe 180 or 240.
Finish with 320 maybe.
Then rinse and dry-
Then for sealing I would recommend you test for porosity and seal or"not" accordingly.
So the not part is that Dakota mahogany is pretty dense.
Because its honed the surface is like a thomas english muffin.
Full of nooks and crannies-where the soiling/darkening by the trafficked areas found a home.
We have used silicone dioxide sealers and found they work on this type of surface.
They seem to bond to the surface and become super phobic meaning they repel oil, water and dry soiling.
We get them from overseas but there are companies selling them here in the states.