Is IoT Python SDK broken with Raspberry Pi?

I've tried to reproduce the issue on my Raspberry Pi 4. The tutorial works as expected on my environment with Python 3.7.3, awscrt 0.12.1 and awsiotsdk 1.7.1.

pi@raspberrypi:~/aws-iot-device-sdk-python-v2 $ pip3 show awscrt
Name: awscrt
Version: 0.12.1
...

pi@raspberrypi:~/aws-iot-device-sdk-python-v2 $ pip3 show awsiotsdk
Name: awsiotsdk
Version: 1.7.1
...

Also, as I see from the error message you shared, you're testing on Python3.9, so I downloaded and installed the Python3.9 to simulate your environment. Again, the tutorial works as expected. I'm sharing my test outputs to help your troubleshooting. PS: I've masked some identifiers with ** characters.

pi@raspberrypi:~/aws-iot-device-sdk-python-v2/samples $ python3.9 --version
Python 3.9.9
pi@raspberrypi:~/aws-iot-device-sdk-python-v2/samples $ pip3.9 freeze
awscrt==0.12.1
awsiotsdk==1.7.1
pi@raspberrypi:~/aws-iot-device-sdk-python-v2/samples $ python3.9 pubsub.py --topic topic_1 --root-ca ~/certs/AmazonRootCA1.pem --cert ~/certs/**-certificate.pem.crt --key ~/certs/**-private.pem.key --endpoint **-ats.iot.eu-west-1.amazonaws.com
Connecting to **-ats.iot.eu-west-1.amazonaws.com with client ID 'test-**'...
Connected!
Subscribing to topic 'topic_1'...
Subscribed with QoS.AT_LEAST_ONCE
Sending 10 message(s)
Publishing message to topic 'topic_1': Hello World! [1]
Received message from topic 'topic_1': b'"Hello World! [1]"'
Publishing message to topic 'topic_1': Hello World! [2]
Received message from topic 'topic_1': b'"Hello World! [2]"'

So, here are some action points that can help troubleshooting the issue:

• Can you check if you have, at least, those versions of packages by running pip3 show <package-name> commands?
• Can you check if you're providing correct certificates to the python3 pubsub.py command? Please notice the match between certificate file extensions and the parameters.