Microsoft has said that they will offer an additional 12 months of security updates (only) to consumers for $30. But that's really just kicking the can down the road.
When Windows 10 becomes unsupported, it will most definitely not be safe to use on the internet. No amount of antivirus software can mitigate this, because the security weaknesses that will not be fixed are security weaknesses in the Windows code, and no third party can patch Windows code - only Microsoft can do this.
Moreover, it's fantasy to believe that one can gain Windows 11's security improvements by installing Windows 11 on unsupported hardware, because the most important security improvements in Windows 11 rely on the very hardware that is missing in an unsupported computer. For this and other reasons, I do not advise anyone to install Windows 11 on unsupported hardware, particularly because Microsoft recommends against it.