IMO, it would be neat to see a government provided "gig brokerage" of sorts that handles the dispatch of things like this (even including long haul delivery, maybe even a mechanical turk equivalent).
When the service is ultimately provided by a contractor, what's the point of having middlemen compete?
Any of us are free to start such a thing right now, if they wish to spend the time putting it together and running it.
(But even as a socialist, I think that this is approximately the last thing that the government should be in the middle of.)
Remember to factor in investors' motivation to extract capital above all else. Short term profit taking is an invisible fist.
I remember Postmates used to be able to deliver from any restaurant or store in your local area. Those were the days.
How big of a thing must it be?