In that case you should assume that FedEx will put them all out of business. There's a lot more going on than "delivery".
I wouldn't turn to DoorDash to deliver live lobsters to me from Maine overnight, and I wouldn't turn to Fedex to get me food from down the street. Those are very different businesses requiring very different infrastructures. Therein lies the problem for DoorDash: they are not that different from Uber. They have similar core competencies, but Uber is vastly better known and financed.
Uber, DoorDash, whatever, they're services glued together with server-side logic and mobile apps.
Fedex, UPS, and I'll even lump Amazon in there. These are logistics powerhouses. Their physical world equipment isn't a liability, its their advantage. Fedex and UPS have knowledge on how to manage a fleet of hundreds of aircraft, thousands of long-haul tractor trailers, tens of thousands of local delivery trucks, and hundreds of thousands of employees.
Your app does not have that. You have users. You have VC money. And while you might think you're more agile than logistics dinosaurs, they have the upper hand. Good luck.