I had the same question, then watched the video to get the answer.
You can Google Hotwire with Django, or Laravel, or many others (https://hotwire.io/frameworks).
The linked page shows only integrating Hotwire with Ruby on Rails, giving me my original impression.
Framework agnostic but Ruby-only it seems.
If your backend can send templates down the websocket, you can use Hotwire.
Rails has a lot of affordances for Hotwire and is the back end framework for which Hotwire was originally written.
I had the same question, then watched the video to get the answer.