One click to navigate to the parent folder — right from the Finder toolbar. Just like ⌘↑, but always visible.
Installation
Download the DMG from the link above, open it, and drag OneUp.app to your /Applications folder.
Open OneUp — macOS will block it because it's not notarized. Go to System Settings → Privacy & Security, scroll down, and click "Open Anyway". Notarization requires an Apple Developer account — which costs $99/year.
The Go Up button appears in your Finder toolbar automatically. You can close OneUp — the button stays.