report on offers displayed to a user of how many users saw the offer on a given page

Hi,
we are trying offer decision management to deliver offers in both web and mobile app.

we are able to get offer propositions by passing decisionscope to the sendEvent.

Once offers displayed we are calling "decisioning.propositionDisplay" event.
how does the stitching happens if we don't pass identity or page details in the below sendevent?
where can we see proposition event fired and where cab we see offer decision report?

alloy("sendEvent", {
"xdm": {
"eventType": "decisioning.propositionDisplay",
"_experience": {
"decisioning": {
"propositions": [{
"id": propositions[0].id,
"scope": propositions[0].scope,
"scopeDetails": propositions[0].scopeDetails
}],
"propositionEventType": {
"display": 1
}
}
}
}
});