Aside from ivermectin, and also aside from Zelenko's vitamin protocol, here's one that I personally used before hearing about those remedies, and that I found tremendously effective, making a big overnight improvement. https://www.spiritofchange.org/nebulized-peroxide-a-simple-remedy-for-covid-19/

But I'd try the other ones first because pills are so much easier, and only do this if breathing becomes difficult or the ivermectin doesn't help or isn't available.