ServiceM8 now supports Sign in with Apple, making it possible to create a ServiceM8 account with an Apple ID, then sign in fast on a day-to-day basis using Face ID, Touch ID, or a passcode.
When creating an account, there is now an option to 'Continue with Apple' to create the account with the Apple ID linked to the device. Once the account is created this way, you can sign in using the 'Sign in with Apple' options on the login screens of the app & online dashboard.
It's also possible to convert an existing ServiceM8 login (i.e. one which uses an email address + password) to use Sign in with Apple.