dateutil.rrule.rrule's dtstart and until flags are both compatible with date as well as datetime and will convert from the former to the latter. See here.

I'm assuming that the typeshed should reflect the types as actually implemented, as opposed to how they're documented - dtstart is passingly referred to in the docs as a "date", which is a bit ambiguous but doesn't create any problems. But until is mis-documented, saying:

If given, this must be a datetime instance specifying the upper-bound limit of the recurrence.

... even though the code will happily convert from a date to a datetime.