This android application provides a widget for your home screen that shows the current time in Metric Time (Decimal Time). You can read more about this time format here https://en.wikipedia.org/wiki/Decimal_time.
You can download the app from F-Droid. Please note F-Droid signs the APKs themselves using a different key than the one used to sign the releases on GitHub. If you switch between providers you will need to completely uninstall the app and then do a fresh install using the other provider.