Logged-in users can import any public app on GitHub into Glitch. To make it easy for them to do so, you can add a link on your GitHub page that will import the repo you specify to Glitch, no account required.
You can also Remix a Glitch app.
Import URL format
Import URLs have the following format:
Populate environment variables on import
You can also populate the values in a project's .env file on import. This can be used to automatically set up a project with credentials or config settings already in it. Just pop the variable names and corresponding values on the end of your import URL, like so:
Generate an import button
Your GitHub project's import URL:
Grab the button code
Here's what it'll look like: