The OSMcodes infrastructure is under testing and construction.
OSM.codes is the "OpenStreetMap Codes", and a project maintained by AddressForAll Institute.
OSMcodes are sovereign decisions of each country about its geocodes, and some countries are implementing it. Postal and Scientific OSMcode applications are interoperable.
Postal OSMcodes, by jurisdiction:
(draft) Scientific OSMcodes and scientific grid, by country: