So here is my recommendation to Kamala’s advisors:

Land hard on school shootings.

Do you think federal gun control policy is a high priority for voters in WI, MI, and PA?

Personally, I think Kamala needs to land hard on the economy and abortion. Abortion, because it's the Democrats' best issue among issues that have high saliency among voters. The economy, because it's the most important issue for most voters.

I think Harris should mostly (but not entirely) be taking this debate as an opportunity less to engage with Trump, and primarily as an opportunity to speak to the viewing audience. She should have her points that she wants to communicate to the audience, and they should mostly (but not entirely) be points about her positions and not about Trump.

Gun control might be a small part of that - you can't not mention it in the aftermath of yet another school shooting - but I don't see that it's a critical issue that Harris should go out of her way to stress.