I don't think that grid will be able to do that, you'd need some kind of state aware component or function in your compiler/SSG that updates the state of your "

I don't think that grid will be able to do that, you'd need some kind of state aware component or function in your compiler/SSG that updates the state of your "mosaic" based on your own settings, so that it can calculate the best possible layout as new items are added to your site and then render/generate it.