Django supportsasc(nulls_first=None, nulls_last=None) anddesc(nulls_first=None, nulls_last=None), but DRF does not.
Even if you write your own OrderingFilter which orders the results with nulls last, CursorPagination will override that in:

if reverse:    queryset = queryset.order_by(*_reverse_ordering(self.ordering))else:    queryset = queryset.order_by(*self.ordering)

My suggestion is to add a configurable class variable that let's us configure whether nulls will be sorted first or last. Alternatively it would be helpful if ordering was extracted to a function that could be overridden.