Every Google account in its own room on your Mac, fully isolated. Each one is the real Gmail web UI, with Calendar, Drive, Meet, and Gemini. No server, no subscription: pay once ($19 launch price, $89 after). Switch with ⌘1-9. Native Swift, a 12 MB app. 14-day free trial, no card needed.
Looking beyond Orbit for Mac? Try Mimestream for a native Gmail feel on macOS, Boxy Suite to manage Gmail, Calendar, Keep, and Contacts in tidy Mac apps, Cron for pro-grade scheduling, or Sidekick Browser to separate work profiles fast.