Is it possible to annotate already united annoated querysets using Djnago ORM without raw SQL

Question

I annotate two querysets

queryset = Statistic.objects.all()

daily_statistic = queryset.filter(
    created__gte=last_week_date,
    statistic_type=StatisticType.DAILY
).values(
    *self.ATTRS_TO_GROUP_BY
).annotate(
    character_count=Sum('character_count'),
    word_count=Sum('word_count'),
    segment_count=Sum('segment_count'),
    token_in=Sum('token_in'),
    token_out=Sum('token_out')
)

today_date = timezone.localdate()
today_statistic = queryset.filter(
    created__date=today_date,
    statistic_type=StatisticType.DEFAULT
)
today_statistic = today_statistic.values(
    *self.ATTRS_TO_GROUP_BY
).annotate(
    character_count=Sum('character_count'),
    word_count=Sum('word_count'),
    segment_count=Sum('segment_count'),
    token_in=Sum('token_in'),
    token_out=Sum('token_out')
)

But then I need to unit the querysets described abowe and perform "group by" by ATTRS_TO_GROUP_BY to obtain weekly statistics.

When I try this with the following code

combined_statistic = daily_statistic.union(today_statistic)
combined_statistic = combined_statistic.annotate(
    total_character_count=Sum('character_count'),
    total_word_count=Sum('word_count'),
    total_segment_count=Sum('segment_count'),
    total_token_in=Sum('token_in'),
    total_token_out=Sum('token_out')
)

I obtain

django.db.utils.NotSupportedError: Calling QuerySet.annotate() after union() is not supported.