The setup requires a couple of steps, so follow along:
- Enable Developer Options on your phone by going to Settings -> About phone -> Build number and tap that several times until you see that you're now a developer.
- Now go back to Settings -> Developer options and find Force activities to be resizable (it shows at the bottom of the list for me). Enable it.
- Reboot your device.
- Install Taskbar from the Play Store.
- Enable Freeform window support in the app. Then turn Taskbar on with the toggle at the top of the app. You'll now see a floating app drawer icon in the bottom left of your screen.
- Clear all your recent apps, because they need to be freshly launched to open in Freeform mode.
- Go back to your homescreen and tap the Taskbar app drawer icon. You'll see the pop-up with the app list. Close it and reopen it a couple of times, until you notice the launcher disappear in the background and only the wallpaper remain.
- You can now launch any app and it'll open in a freeform window.
I followed the steps to test it and at first, the apps were opening as usual, but I rebooted my Nexus 5X once more and it worked like expected. You can move the freeform windows around, tap and hold on any border to resize them, and switch between them as usual with the Recents key.
Taskbar is free so you can grab it now and test it out on your Android Nougat device. Freeform will work on phones and tablets, but obviously its benefits are limited on smaller screens.