How about Ultra light Retractable #Legs (may be Six) so that it can Deliver on Foot also if required. People might get afraid of Flying Drones approaching them straight away… Suppose X orders the Pizza, Drones flies for delivery, The person X is in his Home or Office or Apartment or Park or anywhere. X can be found but straight flying is always not possible. Effective #Walking option will be good, i think, if not now may be later version. If we design well, i dont think we’ll need any Extra Drives, these 4 can be utilized… or may be 2 more needed… and if proper Materials and Mechatronics choosen it’ll remain light weight. Only 4 Legs might also work fine.