I’ve just installed an app that essentially allows me to do it the other way around, by grouping single products together with customisation options like showing the variant as image or colour in the icon. It would be great if this can be done in the theme itself.

Currently this option on collection pages would cause issues with pagination, due to showing more items per page.

An alternative solution we could look into is creating a section, like "Product variants grid" where you can select what products to pull variants from?

Then you could create a custom page template and use the section in that too.

We'll mark this under review as we will have a look into a custom section - let me know if this is something that would fit your needs!