website design – Out of stock alerts for a product page with multiple variants?

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.

Any advice/research? Thanks!