[Fixed]-Should we connect to AWS SNS every time we send a push notification?

The Client classes in the AWS SDK are just wrappers around other lower-level HTTP clients that interface with the HTTP REST methods of the AWS APIs. They are very light-weight so instantiating and destroying a Client instance on each HTTP request to your DJANGO app should be just fine — you will incur little overhead. I wouldn’t worry about shared state clients like you might utilize in Java or other multi-threaded application designs.