Out of stock alerts for a product page with multiple variants? [closed]

I'm a junior ux designer currently ideating a solution for out of stock alerts.

Our products have between 3-4 variables, and these will differ for each of the colours. (So for example.. colour, material, size, condition). We currently just have the unavailable options crossed out, but no option to notify users of items coming back into stock.

Most articles that I've come across talk about stock alerts for single items.

Most of our users are mobile so this somewhat limits screen space too.

Here is the website currently, so each colour would have different availabilities in ram, storage, condition. Currently we have no way for users to sign up for alerts that will notify them when one of those variables comes back in stock. Basically if a user encounters a product with the specific options they want, we would allow them to sign up for an alert when a device matching those exact specs becomes available.

I'm not quite sure how to communicate to the user that the options are out of stock but that they can receive notifications for when an item with the variables they chose has come back in stock.

We also cannot tell how soon these products will be available so can't provide an estimated timeline or a pre-purchase option.