The best alternatives to App Pier for MacOS are Alfred, Lacona, and GeekTool. If these 3 options don't work for you, we've listed a few more alternatives below.
What do you think of App Pier for MacOS?
AssemblyAI— Speech-to-Text API with superhuman accuracy
Alfred is a productivity application for macOS, which boosts your efficiency with hotkeys, keywords and text expansion. Search your Mac and the web, and control your Mac using custom actions with the Powerpack.
Using spatial memory to launch and switch apps in macOS creates a surprising productivity boost. Charmstone is a unique but simple spin on cmd+tab & the dock that easily fits into your workflow. It's especially great if you hide your dock.
AppSwitcher For Beautiful Presentation of your Apps. On the iOS-like Big Sur. Switch between Apps and Switch to, show only that App. "Hide Others Always On". Have a Clean Desktop + App.
SwitchGlass adds a dedicated application switcher to your Mac. You can customize its appearance, size, and position on each attached display. Use it to bring one or all of an app’s windows to the front, or as a drag-and-drop target to open files.