I currently use Swiftly Switch. 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?
This is not related. This is the stock Android "currently open/recently opened apps" display.
This bar, with gesture navigation, swiping up slightly and letting go
or swiping up normally with 2-button navigation (which sadly got dropped)
or pressing the ||| (Samsung) or ◻️ (Stock Android) using the still available legacy 3-button navigation
This does not replace a custom set list of apps you would like to quickly access. Maybe something like this could also be integrated as a notification.
I use a patched version of Nova Launcher Prime, working without a Google Account. GrapheneOS, has no internet access. I tried all FOSS launchers and still nothing comes close.
But the recent apps thing is not a launcher part, even though it is broken when removing Trebuchet on LinageOS (trust me, tried it)