Use MacAfee on a Onn Roku Smart TV

I don't know if McAfee is compatible with Smart TV sets; however, if it was, I wouldn't use it because McAfee is too "bloated" for devices with limited resources, like a Smart TV.

If your router has a firewall, this would be adequate protection.  I couldn't find a Onn website but some manufacturers offers a virus scan feature.

If you suspect your TV is infected, you could always reset to its Factory Default settings.

I'm unsure of the OS for Onn TV sets but if it's a Roku OS, it's based on Linux, highly modified and difficult to infect.