Yes they have, from the onset. It was only considered BECAUSE there was a plausible mechanism. HCQ is able to transport zinc ions across cell boundaries, which

Yes they have, from the onset. It was only considered BECAUSE there was a plausible mechanism. HCQ is able to transport zinc ions across cell boundaries, which is critical to getting zinc bioavailable within a cell. Zinc disrupts the viral RNA copying which is part of the replication process. So zinc + HCQ should slow down the progression of the disease by decreasing viral load. Notably most studies did not pair HCQ with zinc, and most focused on near-terminal patients for which slowing down viral replication would be too little, too late.