I currently use Swiftly Switch [https://play.google.com/store/apps/details?id=org.de_studio.recentappswitcher.trial]. It is an app that adds a small bar to the side of the device and by swiping that part, I am shown a list of apps of my choosing. This allows me to open apps much faster. Sadly, it is not open source. Is there something similar but open source?