How can customers sign up for product availability notifications?

[Dannypro]

I am looking for an app/way to enable my customers to sign up to receive notifications if I stock a particular product/type. My store sells overstock items so my inventory is constantly changing and is never the same. I want a way for customers to sign up to receive a notification if I ever get a particular product in stock in the future. I.e. if a customer is looking for an entertainment center, they can sign up to get a notification if I ever create a listing for that product type. I am not looking for "back in stock" alerts. I am looking for alerts for any products I list in the future.

[PaulNewton]

If future products are unknown vs "back in stock" then an issue you'll have with this is ambiguity in what people request to be notified for versus what possible items you'd ever get and how you decide to name them. Because naming is hard, harder if doing this in multiple languages.

So you'd need to predefine broad top level categories otherwise it's just throwing things at the wall and hoping something sticks.

Say you have this sign up and I put "stereo stand" that's super specific but if you ever get that product you may put "stereo shelf", or vice versa so no match is ever made. 

Or whatever tool does this needs to let you disambiguate and categorize and search such sign ups.

An app like mechanic can be scripted to create such automations though no UI.

Good if you can predefine the words/terms customers sign up for.

https://tasks.mechanic.dev/tutorial-trigger-a-task-from-a-contact-form-using-webhooks 

It's possible shopify-flow or shopify-mail can be utilized for parts of this but it have to be tested and confirmed.

A possible app area to look at is product-research apps or page landing apps that let merchants test interest in a product idea; you'd just repurposed that for use with the overstock model.