This repo is an example of how one might use PowerShell with Pester and GitHub Actions to casually monitor the status of multiple web servers and their certificates. By "casually", I mean that this is using GitHub Actions with a cronjob trigger so at best you would know a system is offline in ~5 minutes.
The original intent was to monitor the certificate status of a few sites and find out if the certificates were approaching expiration. Therefore a GitHub Action running a few times a day more than meets that expectation.