designing a usability test for a homepage that nobody visits

I'm tasked with planning a usability test for a health information website's homepage (think WebMD but more of a public service/encyclopedic website - not commercial, not for profit).

Emphasis on homepage - understand that the vast majority of the site exists as child pages - detailed encyclopedic pages about symptoms, treatments, etc.

So of course as you might imagine, the vast majority of site users arrive directly to child pages via Google (e.g. "symptoms of COVID"). And this works fine; the child pages have usability tested successfully.

The homepage has long existed before I joined the team, and wasn't necessarily designed with any specific user goals in mind. It suspect it was more of a "well we have to have one anyway so..."

My struggle is: If the home page serves almost zero utility for the vast majority of visits to the site, then what kinds of tasks do I propose for evaluating the "usability" of a homepage?

Seeking input from Stack Exchange on what kinds of usability tests are appropriate for a homepage on a massive information website, understanding that very few users need to use it, as they arrive to their targets via Google search successfully anyway.