You should be able to draw on a mapview.

Nobody has claimed this yet.

### What is the problem or limitation you are having?

So, clearly an enhancement request: I was considering briefcase, toga, and MapView for a drone telemetry app I've been screwing around with - but I quickly discovered that (a) there's no way to create visually different pins or icons (i.e., home vs the drone) and there's no way to actually draw the route the drone is taking.

### Describe the solution you'd like

I realize #3326 has already been opened about improving pins, so that's a thing, although I'm not entirely sure pins are actually the correct solution for the use case I described above.

Ideally, what I would like to see is the ability to layer a canvas Widget on top of the MapView widget, giving full access to that capability.

### Describe alternatives you've considered

Honestly, I'm a backend dev who doesn't really know much about python or about making a GUI app that supports everything from MacOS to GTK so I can only describe what I'd like to see, I can't really offer an intelligent list of alternatives.

### Additional context

Check out https://github.com/koen-aerts/potdroneflightparser for an example of what I'm trying to do. Unfortunately, that project no longer builds on MacOS (my preferred environment) which is why I started looking at doing my own.

Start by reviewing the existing MapView and Canvas Widget APIs and the related pin work in #3326; the issue names no files or tests. Clarify the cross-platform overlay scope, then define acceptance around drawing a route and visually distinct map markers on supported platforms.

Written by the indexing model from the issue text.