Assign floaters (or groupings) to in-app and/or global keyboard shortcuts.

Use the shortcut title bar menu, or Window menu → Shortcuts to assign a note or grouping to a specific in-app shortcut (⌘0 through ⌘9). Then you can set up global keyboard shortcuts in Settings → Global Shortcuts to reference your in-app shortcuts by number.

Use Floaters' main list as your starting point

Press ⌘⌥^⇧L from any app, or ⌘L from within Floaters to bring up the list window. Customize, create, and reorder sections (recent, currently open, favorites, etc) and display options in the Settings window.

Change focus within a grouping by holding ^⌥ (Control + Option) and pressing the ↑→↓← arrow keys.

When creating a new floater, link it to a side of the currently-active floater using the arrow ↑→↓← keys

This will link the existing floater with the new one in a grouping. Alternatively, you can press various other keys to skip linking and instead place the floater in a specific position on screen.