How to make such a hint for an additional field?

Hello,

This is possible via an override view ( documentation ) but a bit complicated!
In details you have to :
- Create an override of your product view (product/show_default).
- As a required text information create a classic Joomla article
- Add a button to display your popup that point your relative article(see how to create your own popup, here )

Hope this will fit your needs.
Regards

Hello,

An e-commerce site has many needs that vary enormously depending on the type of business model, and therefore needless to say that we have bigger fish to fry long before that.
Which doesn't mean we'll ever implement it.

But here, this type of feature is very cosmetic, and can therefore be implemented in your HikaShop by website creators in many different ways, a bit like I described it to you previously, by an override and other custom.
Regards