curl --request POST \
  --url https://{subdomain}.nudj.cx/api/v2/integration/rewards/{rewardId}/purchase \
  --header 'Content-Type: application/json' \
  --header 'x-api-token: <api-key>' \
  --data '{
  "amount": 1
}'

{
  "success": true,
  "rewardEntryId": "<string>",
  "assetIds": [
    "<string>"
  ]
}