VSCode is pretty cool, and you don’t even have to download and install it!
Here’s some info on how to use it generally in the web. https://code.visualstudio.com/docs/editor/vscode-web
The cool stuff is using it in Github and Azure DevOps…
I’ve been using this feature for a while now. VSCode is accessible on a github repo by pressing . (dot) on any repository you are browsing. This could be your own repo but also a public repo. It enables you to quickly view files and edit them without having to clone them to your local machine. Github codespaces are the next level if you want to actually run an application or an extension etc, but the code editor works great for just viewing and editing quick files from a repo.