Can we allow a customer to reserve the entire resource (all its shares) for special price?

Yes, you can. Let's say, you already have a resource with shared price options. For example, a small cafe-bar, which has 4 tables.

Now create another price option. Click on +.

Enter Name e.g. "Whole restaurant", select an Exclusive type, specify the price, and enter a description if required. Save it.

Now there are 5 price options available for booking. The configuration will look like this:

If you want to add a description for the Shared radio button, go to the Text tab in the widget settings. Add a translation with key RESERVATION__SHARED_DESCRIPTION.

It looks like this on the widget:

Check the result on the widget: