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 one shared price option. For example, a cafe-bar which has 10 tables.

1. Create another price option.
2. Enter the name and description if needed.
3. Select the type — Whole resource.
4. Set the price.
5. Save.

Now there are 2 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 Localization panel in the widget settings. Then add a translation with a key RESERVATION__SHARED_DESCRIPTION.

It looks like this on the widget:

If you book the whole place shared price option for separate tables will disappear. And vice versa, if you book at least one table, the whole place option will disappear.

Check the result on the widget: