You can use the canvas to create various shapes, artworks, logos, texts—anything you like. Once you buy pixels like this, they remain on the site permanently, and no one can take them away from you.
I've seen this many times before, but the format is advertising type. Vod is right; you should extend the domain for at least 3 years to attract people.
Compared to the past grid-type platforms, what unique features does your platform have compared to all the past grid platforms?
Honestly, I am having a hard time checking those grids that have been occupied. It's better that you create a video tutorial on how to use your platform as an example.
A video tutorial, extension of the domain, and the right marketing strategy, and you have a chance to fill those grids and succeed where many fail with this type of platform.