Bus stops here: Shanghai lets riders design their own routes

What does that mean? The links doesn't help explain it much?

In the UK/London there are some bus routes where you just stick your arm out and the bus will stop to get you where you stand ("hail and ride") and equally you can just ring a bell when onboard and the driver stops as soon as there is somewhere convenient to let you off. The route is fixed though.

Is it that sort of thing?

What routes are those? I thought you can only be picked up/dropped off at designated stops

The route through my village is hail and ride although most of the bus drivers seem to disagree.

So there are virtual stops all over the city. You book a ride let's say city center to your home. The service integrates this route into existing rides or create a new ride. It might stop 5 times on the way to your home and pick up people and drop them. And you as a passenger won't know the route in advance. And it will not be the fastest to your place in most cases.

I guess this is what you call "ride sharing". It is like your parents picking you up from football and realizing the kid from the other part of the town also needs a ride so they make a huge detour

Many routes have "hail and ride sections" without designated stops. You can't get off, but can hail and get on at any point. Here's a list for London [1].

[1] https://bus-routes-in-london.fandom.com/wiki/Hail_and_Ride_b...