Attributes without Variants

A question about attributes.
Imagine I am selling shoes and want to give some the attribute BLACK so the costumer can filter based on it and also at the end of the month i can check if black shoes (different products with the the attribute BLACK) sell better or brown shoes so I can order new products based on that.
In this situation, I add attribute black if a shoe model comes in different colors (variants), but if a shoe comes only in black; Do I have to make a product with 1 variant?
Is reporting based on this attributes possible?
Imagine you only sell iphone-x 128G, but not any other iphone-x variants.
hope I’m not missing something here.

If it is only one model, you do not have to create variant unless you are not generating any report on the variant. I suggests to create it as a variant if you have a slight chance that the item will have another variant in the future.

There is Item specification but you wont see it unless you check the show on website option (in Items), which solves the website part of the issue.
Also it seems to only work for the website and no sale reporting based on specifications are possible.
will try custom reports soon.

Well there seems to be no way of using filters with specs.
Also there is no way of adding attributes without variants.