I used to use Nod32 myself, but I found that I couldn't work with the latest version at all with NVDA, and I wasn't all that comfortable with the idea of staying a few versions behind just for basic accessibility. Plus, it nagged me all the damn time to upgrade to the latest version. So, I decided that when I bought my new computer, I'd give Windows Defender a try. I figured that if something went wrong, I know how to format my system/keep current backups/get myself out of any horrible situation that might arise. I haven't kept up with the latest AV test results, so was unaware that it had been scoring higher than before in recent months, but it adds up. I'm pretty happy with it. I do keep Malwarebytes and Clamwin around as backups, though. I don't think it hurts to have a backup plan inside of another backup plan.
Where can one find this Kaspersky add-on, though? I wasn't aware that it existed. I don't plan to purchase another antivirus for myself soon, but it would be nice to have in case someone else I know wants to try it. It's definitely not an official add-on; I've never seen it listed on NVDA's website.