You can add any custom folder under This PC in File Explorer in Windows 11/10 by editing the Registry by following this tutorial. In Windows 11/10 File Explorer Navigation Pane, if you want, you ...

The Navigation pane in File Explorer shows Quick Access, This PC (including hard drives), Library folders (such as Music, Videos, Pictures, etc.), and Network drives.

Customize File Explorer with some useful Registry tweaks to declutter menus, speed up browsing, and restore classic features.