Can you activate service intervals with both hours and days, whichever comes first?

Yes. When the service object is marked as Run time based, more fields open in the service interval. However, you can only enter 1 day interval but several hour intervals. The system will take the one that comes first. The day interval is filled in on the first interval.

Example: if the machine has run 500h before 365 days have passed, the operating time will be the first time the system detects.