MongoDB Compass - Are Aggregation queries $set executed or only previewed?

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4

I misunderstood what you said.
$set in an upsert sets the document to be upserted.
Here it is in PHP where I add a pot to a collection of pottery:

public function upsert_pot(object $doc): bool {
        $doc['price'] = new MongoDB\BSON\Decimal128($doc['price']);
        $uresult = $this->mongodb_db->pottery->updateOne(
                ['potnum' => $doc['potnum']],
                ['$set' => $doc],
                [
                    'upsert' => true,
                    'writeConcern' => new MongoDB\Driver\WriteConcern(MongoDB\Driver\WriteConcern::MAJORITY)
                ]
        );
        return $uresult->getModifiedCount() > 0 || $uresult->getUpsertedCount() > 0;
    }