I just took a look. For the USA site they do have that feature, but since the 2020 Fastroad SL is apparently not shown as in stock by any of their dealers, then it's not apparent that they will show you where there is a bike. In this case they can't cause they don't know either.

Look at the 2021 FastRoad SL 3. https://www.giant-bicycles.com/us/fastroad-sl-3-2021

Select a size. I chose medium, local pickup blah blah blah. Underneath it shows where they have available bikes of that size in stock and how far they are from what they think your location is.

Call before you drive all that way though. No guaranty the inventories reported by stores are that exact or that it won't be gone by the time you get there.