Make the Ultimate To-Do List a Progressive Web App
Progressive web apps are coming to Windows and Android devices. Apple may slowly follow along (or lose big?). PWA's hold the promise of write-once/run everywhere. I now have my outlook.com e-mail apparently running as a PWA in Chromium-based Edge. At about 38 minutes in the 11/27/19 Windows Weekly podcast, the significance of PWA's to Android and Windows development is discussed. Android PWA's should be able to run directly on a Windows 10 computer, etc.
https://twit.tv/shows/windows-weekly/episodes/649 (audio only available from dropdown beneath video player)