None. They aren't needed on Android TV. The OS self-manages background apps and cache. If needed, you can clear device cache in storage settings or by just restarting the device. Don't need anti-virus either. Malwarebytes is good to have thougn if you sideload apps. Best to just get sideloaded apps from a trusted source though.

Sorry for Off topic I have also a 7303 and I want to ask you, does your Bluetooth works?

Mine doesn't find any device, and is getting me crazy