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Thanks, that helps. In fact I've spotted a typo in its technical language:

"by binding itself permanently with ferriprotoporphyrin (of the Hb group Eme)"
should read:
"by binding itself permanently with ferriprotoporphyrin (of the Hb group Heme)"
at least in US English. The Brits would spell it Haem.

This is NOT new information but rather the most accepted explanation for how HCQ kills malaria parasites. Further details on that are found on this Wiki page.

Malaria parasites eat hemoglobin, degrading it into its parts. It finds single heme parts toxic so groups them into inert lumps. HCQ (and related drugs) bind to heme in a way which blocks that grouping. So all the single heme left from eating hemoglobin kills the parasite. Normal heme = Protoporphyrin IX + Iron. Covid wants to steal protoporphyrin IX for use in its own replication. The best supply of it in humans is the heme in our hemoglobin. But the same bound HCQ also blocks Covid from using that protoporphyrin IX unit. Without which it can't make more Covid particles. Give HCQ first and malaria parasites die from eating you. Give HCQ first and Covid can't multiply into enough to harm you. Give HCQ late and your amount of Covid, already sufficient to harm you, continues to harm you. Enough to prevent malaria is likely enough to prevent Covid. No, Covid is not the flu. Surprisingly, it's more like malaria, without needing mosquitoes!

Sadly, for the many zinc fans, I don't see where zinc plays any role in this mechanism. It might in other suggested mechanisms of action. Sorting out their real and relative importances should be researched and produce some PhD theses, AFTER we use the drug to defeat the dang pandemic!

Covid's breaking iron from heme to steal protoporphyrin IX, dumps iron in the lungs resulting in its unique lung CTs. Attacking heme reduces the blood O2 carrying capacity even while lungs are working ok. Breathing higher % O2 helps that even though mechanical ventilation won't.

This brings back memories of Derm board studying. Umpteen different genetic disorders affecting synthesis and degradation of heme are lumped together as "porphyrias." Because most of them include some variation of the word "porphyrin" in their names. To keep them straight you had memorize the whole pathway. Never would have expected that stash of trivia to help me with Covid.