I found a detailed 4-part video on 5th generation valve cover gasket replacement. I learned a better way to remove connectors in part 1:
5th Gen Toyota 4Runner 4.0l: detailed valve cover gasket replacement (LH) - YouTube
It appears to be more than 2-3 hours labor. A Napa online repair estimate is $756. Online mobile mechanic repair estimate is $854.
Here's another video where a lot of oil was pooling in one spark plug chamber.
5th Gen 2010-2021 4Runner Valve Cover Gasket Replacement - YouTube