How can I convert a glTF metallic-roughness map into two separate roughness and metallic maps?

All those xy-maps are very dependent on the shader setup and the actual engine… (and i’m not an expert in this) … (but) if you search for this… you can find an overhelming amount of posts… for example:

or (no solution yet… but mayne interesting info to start with…)

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The next is is a bit different topic… but also struggleing with the differences used in different aproaches…