I've been testing out a bunch of different torrenting/streaming apk's and know that it can be risky. I'm mainly concerned with ransomware and getting locked out of my Nvidia Shield TV or anything else that could happen and survive a factory reset. Would any android AV products be good? I just installed an AVG apk but don't see if it has ransomware protection.
Also, is there anyway to auto update apk's?
Anyway to scan apk's before installing?
Honestly the best way to stay safe is to not sideload. I don't believe it's that particularly dangerous, especially on AndroidTV, but you never know.
But sometimes it is needed. What I do is to download it to my phone using GooglePlay and then extracting the APK. Many file managers allow that and I put it on a cloud drive or wireless transfer the APK to the device to install.
If you don't have an Android phone then I believe there are APK file scanners on the web and hash checkers. There are a few so you'd have to Google it.