Shade

A dark display.
A working Mac.

Keep Computer Use running while your built-in display is dimmed. Move your trackpad to return, then let Shade dim again when you step away.

Drag Shade to Applications. Turn it on from the menu bar. Choose a dim delay, record a shortcut, or enable Wake on touch. The brightness-up key is always your way back.

Dimming doesn’t lock your Mac. Shade is a privacy band-aid, not security.