You can show both a reservation overview and an interactive sidebar next to a Gravity Forms checkout page.
Reservation overview. The sidebar shows the property image, title, location, check-in and check-out dates, guest count, and pricing summary. You place it next to your form using a shortcode. It reads the booking from the URL automatically, so there is no extra work on your end.
Coupons and add-ons. The Gravity Form reads the quote once when the page loads. Before the setup is finalized, support checks whether a coupon or add-on change properly updates the Gravity Form payment field. If that link holds, add-ons you manage in your PMS carry through automatically. If it does not, add-ons can be built directly inside Gravity Forms as products instead, which gives you more control over how they are presented.
Book Now links. In either case, your property Book Now links point to the Gravity Forms page rather than the default checkout page. Support makes this as a configuration change, without editing plugin files.