In Opensearch, what is the syntax for adding an SNS destination using the _alerting API?

We still seem to be experiencing the bug outlined this question, despite being updated to v1.1 P5.

One of the workarounds suggested was to use the API to create the destination, but, since we don't have any existing SNS destinations, I'm not sure what exactly the syntax is.

I managed to get a destination created using the following, but it's registering as an "unsupported type". Not sure if that's a symptom of the bug or if I screwed up the syntax of the alert destination creation.

POST _plugins/_alerting/destinations
{
  "name": "sns destination",
  "type": "sns",
  "sns": {
    "topic_arn":"arn:aws:sns:us-east-1:000000000000:opensearch-alerting-topic",
    "role_arn": "arn:aws:iam::000000000000:instance-profile/opensearch-sns"
 }
}