Hi,
What do you mean by
But I can't get a 'no stock' message I guess with 'products' that don't have a numbered inventory.
?
In a previous message, you said:
they want that button to change to REGISTER CLOSED when the course is sold out or after a certain date.
Normally, if a product has stock and has no sale end date, or a sale end date in the future, HikaShop will display the add to cart button.
And if the product doesn't have any stock left, or has a sale end date in the past, it won't display the add to cart button and will display a message like "no stock" or "this item is not sold anymore". And both of these texts can be customized to display as a button with the text "register closed" with a translation override and a bit of CSS.
So I'm not clear on what's keeping you from doing what I recommanded. Maybe I don't have a full grasp of your need here.