Not really no.
An EBS/backend server/service can be written in any language you are comfortable writing.
A Twitch extension, is essentially a website, where the front end is “dumb”/has no server side processing/template rendering, and is on a separate server to the backend/database/other stuff.
You an broadcast to PubSub from the config page and/or the front end, but most PubSub stuff will be sent from an EBS, that Twitch won’t host for you, Twitch only hosts JS/HTML/CSS (and any images you want to put on their CDN instead of yours).