I'm searching something like this. I need a general information request feature reffered to each product.
I'm searching it in _ProductDetails viewset but I can't find no similar feature.
I've tried to look into reviews used as information request feature but it is usable only for authenticathed users and does not meet my needs.
Thanks for any help!

This is absolutely possible. You would just need to update your viewset (and potentially the action delegates) to override the standard customer workflow. You can see an example of this in the following Hotcakes site:

http://www.swsvoyager.com/

In it, the visitor can put together a listing of products, and the "checkout" is simply an e-mailed order that then gets handled by a sales rep.

If you need any help with the implementation, feel free to let us know.

https://upendoventures.com/Contact-Us

Thanks Will,
it is not exactly I'm asking for...I'm thinking to a contact form request directly in the product details page, something like reviews but with name, telephone, message (better if personalizzable form) with 'Send Request' button. Would be great if it is integrated inside Commerce administration with the log of past requests.
I've worked along time with Ventrian Property Agent module and there it is present this feature and very times my customers ask for it.
I understand that most likely it is a new feature but could be an idea for future feature!

Scippy:

I don't think we'd be adding this as a feature, nor would we accept it as a pull request. The option/feature you're suggesting is very use case-specific. In my experience, nearly everyone that implements this kind of store does it completely differently. Most often it's overriding the checkout process though, instead of putting a form directly into the product details.

You can still do this though. You could have a SPA-based form built and implemented directly into your product details view of your custom viewset. Then, simply replace the Add to Cart button with your own to open the form (maybe as a mobile-friendly pop-up). You'd also want to add code to your cart and checkout views to redirect to the main store page, just in case someone goes to them directly.