You can put widgets apps and shortcuts on the sub-launcher. It can be easily customized by Drag and Drop.

HINTS
- Devices without software home button might be able to launch this app by double-clicking or long-clicking physical home button.
- Setting below needed with Android 6.0
Open "Settings - Apps - (Wheel Icon) - Default Apps - Assist & Voice input - Assist app" and select "SwipeUP Launcher Free". After that the launcher is launched by holding the home button not by swiping up.

NOTICE
This free version has limitations below.
- The number of items are fixed in 3x4
- Direct call shortcuts are unavailable
- Ads are shown when customization