For reference, I utilized Welcome Pickups for a transfer from my hotel in Oia to Santorini airport for an early morning flight for 45 euros. I would see if the bus stops anywhere near or along the route to your accommodation so you do not have to brave the 30 minute walk. I do highly recommend sunscreen to avoid the risk of being sunburnt by the Mediterranean sun.
If you wish to catch the sunset in Oia, I can attest to the Views of Santorini and Caldera attraction point, seen on Google Maps on the west end of the island. I do recommend getting there at least 20–30 minutes prior due to the large crowds that may be traversing to and from the area. I hope you enjoy your trip, and I am looking forward to following along with the trip report as always!