Actions have special integration with GitHub (e.g. they can annotate the pull request review UI) using an API. If you forgo that integration, then you can absolutely use GitHub Actions like "a container you run scripts in." This is the advice that is usually given in every thread about GitHub Actions.
If you want to make a CI performant, you'll need to use some of its features like caches, parallel workers, etc. And GHA usability really fall short there.
The only reason I put up with it is that it's free for open source projects and integrated in GitHub, so it took over Travis-ci a few years ago.
Devil's advocate: They could make the github CLI capable of doing all of those things (if it's not already), and then the only thing the container needs is a token.
> For a Linux user, you can already build such a system yourself quite trivially by getting an FTP account, mounting it locally with curlftpfs, and then using SVN or CVS on the mounted filesystem. From Windows or Mac, this FTP account could be accessed through built-in software.
