Hey, @Sayfox02 !
Ash here from the Shopify team. Welcome to the Shopify Community!
I absolutely see why in your specific case using the variant set up built into Shopify may not be ideal. I have a couple potential solutions for you to consider. As you mentioned, one solution could be to limit the amount a certain product can be sold in its entirety. This could be achieved with an application like Limit Qty Purchase. The Limit Qty Purchase application allows you to set up a lifetime limit that all products on your shop, or a specific product can be purchased.
My second potential solution is to remove the variants from your product(s) in the products section of the Shopify admin, and use a product options application for the sizes instead. Product options applications allow you to add in selectable options, such as a size, without having those counted as product variants. Using this method, your base product would have an inventory of 5, and then regardless of what size your customer chooses from the options provided by the app, all purchases will reduce from that base inventory of 5.
Here’s a link to our App Store with a number of product option applications for you to consider. Additionally, here’s a list of some that I think would do the job you’re looking for:
- Infinite Product Options
- Product Options Variant Option
- Infinite Options
- Variant Custom Product Options
I’m interested to hear how you decide to proceed. Let me know what you think of these ideas by replying here.