The issue is likely with the directory structure of your layer. For AWS Lambda to recognize your module, the site-packages folder needs to be under the python/ directory in the root of your ZIP file. Here's the correct structure:

python/ lib/ python3.11/ site-packages/ pyodbc/ pyodbc-5.2.0.dist-info/

Make sure you're matching the Python runtime version of your Lambda function (e.g., Python 3.11).