GitLab Runner only for jobs of Pages, for security and easy use

We want to host static web pages on GitLab and build a service easy to use in a manner similar to GitHub Pages.

For usability, we hope to use a shared runner so that users do not need to go through the extra steps of runner setup before publishing a page, but there are security concerns on shared runners.

Is there a way to configure a shared runner that only accept jobs related to Pages?

Or, I will also appreciate feedbacks on other aspects of runner configuration to implement the same purpose.

I am pretty new to GitLab administration, so please kindly tolerate my mistakes.