@fedejko You should be able to join the two sets together, like this, for example (reusing your two queries):
| rest /services/saved/searches
| search title="*Rule" action.notable=1
| fields title
| eval has_triggered_notables = "false"
| join type=outer title [
search index=notable search_name="*Rule" orig_action_name=notable
| stats count by search_name
| fields - count
| rename search_name as title
| eval has_triggered_notables = "true"
That adds a field has_triggered_notables which will indicate if a rule has triggered notable and you can then filter out the results to your liking, for example, to show only the rules which did trigger notables: