It is sad that the hosted version of GitHub Audio does not exist anymore. It is economically not possible to host it on a paid server due to the costs.
These are alternate options :
Host using Static pages. Since, all of it is written in Javascript, https://github.audio can be a static website.
Check out Netlify which is a better alternative to GitHub pages. It also allows setting environment variables which will be required to store GitHub tokens.
Host the app on Heroku. Heroku offers free hosting for a limited number of hours per month. A Heroku instance will be very helpful for a quick look prototype of the project.
It is sad that the hosted version of GitHub Audio does not exist anymore. It is economically not possible to host it on a paid server due to the costs.
These are alternate options :