I have lots of pages on my website, where the main content is made of tables, and cells are just colors.
Think of a time schedule where you would have the busy and non busy times of your post office for example. Some timeslots would be green, other orange, other red.
This table is the center of the page, and SEO-wise... it's worth almost nothing.
We could have a title stating "Best times to go to Post Office XYZ", a legend/caption, and that's it, nothing more for Google to digest.
Cells are designed to host text, which is the SEO content. But in my case, they're filled by a hex code for the color.
I've looked into accessibility best practices, like if our schedule should be screenreader compatible, it's the right direction but it still doesn't fit my specific case.
My value is in these colored cells, and for Google, it's nothing