There's not a lot of evidence (quantitative randomized trials) showing Ivermectin actually helps, but studies are underway that will give us data we need. I've heard good things and bad things about it. Here's an up to date, soberly written article on it:
Unchecked ivermectin use in region is making it difficult to test anti-parasite drug’s effectiveness against the coronavirus.
www.nature.com
The problem with buzzy medicines supported by anecdotal results is that suddenly people start demanding the drug and expecting it to work. The status of Ivermectin is that it's not blessed for COVID-19 use outside of trials, and if a doctor wants to prescribe it, they can use it off-label, but there's no reason to think it's a wonder drug.
That said, I'm a big proponent of using existing (available, cheap) drugs when they can be shown to work well enough to be worth the effort. Dexamethasone is an example, but it's usually helpful in more severe cases.
To the best of my knowledge, no medicine known is shown to be (via randomized trials) particularly useful in prophylactic COVID-19 management, aside from the usual things that support a healthy immune system.