The Pop!-OS launcher is a part of the Pop!-OS shell, which is implemented as an extension on Gnome Shell. You can therefore not install only the launcher.
There are some alternatives that provide a similar minimal keyboard centric possibility to launch applications, find files and do other things.
Albert launcher: a minimal, desktop agnostic launcher implemented in QT
Ulauncher: equally minimal, written inPython with GTK as a GUI toolkit.
Rofi (Wofi if you use Wayland): Very minimal and fast, and fully desktop independent. Available in the standard Ubuntu software repositories, easy to set up for application launching but somewhat more power user oriented when it comes to customization. Comes by default with application launching and window switching, but with some bash scripting, you can create menus for everything.
The Pop!-OS launcher is a part of the Pop!-OS shell, which is implemented as an extension on Gnome Shell. You can therefore not install only the launcher.
There are some alternatives that provide a similar minimal keyboard centric possibility to launch applications, find files and do other things.
There's now two community developed launchers that interface with the pop launcher service :
With theses you have the full power of the pop launcher but in a standalone launcher that does not require gnome shell.