How to make a in stock notification feature that saves the submitted user data to a google sheet?

I have a client with a very specific request. They want a stock notification option on their clothing product pages, ideally a button that opens a lightbox with a form in it.

The form would capture simple stuff (name, address, product and size they are interested in) and then save that data to a google sheet that could be reviewed manually/updated by the client.

There is no need for 2 way sync or anything more fancy than the code adding a new row to the end of the same google sheet each time that a form is submitted.

I know that there are lots of plugins for shopify that save inventory to google sheets but that isn’t what this is. All we want in this google sheet is a listing of these customers and their stock wishes. I haven’t found anything at all close to this on the shopify marketplace and am considering custom coding a popup that opens something like a MightyForm based form, as their product can save straight into google sheets.

Does anyone have a better way of doing this ?