Any language that can listen for incoming HTTPS requests can use EventSub.
This means that Python can do it (although I’m not experienced with that language so unsure what the best HTTPS server lib woudl be). Javascript can do it, a popular NodeJS module for handling the whole webserver side of things being Express which is in many tutorials and guides.
Another option is to use cloud services such as AWS API Gateway and AWS Lambda, so that takes care of the whole web server side of things for you, and you can write the logic inside Lambda functions in a huge range of languages that could then make the stream markers you need to make.