I have hundreds of files in my local directory and I want to treat them as parts of a single file and upload them to s3, I want them as a single file in s3. ideally, I want to use s3fs or boto3 to accomplish this but any other approach is also good.
There is no provided command that does that, so your options are:

Combine the files together on your computer (eg using cat) and then upload a single file using boto3, or
In your Python code, successively read the contents of each file and load it into a large string, then provide that string as the Body for the boto3 upload (but that might cause problems if the combined size is huge)
how to upload multiple files from local to one file in s3