What do you mean exactly by organic maps editing tools? I was using organic maps before to add businesses, but now StreetComplete can also do that (and more!). I sometimes use Vespucci because it is very powerful, but it’s a bit of a pain to use.
Actually, a least some cars (probably more than you think)/have some sort of “emergency” breaking signal, which often result in the usual breaking signal blinking for a while. You need to seriously slam the brakes to see it though. E.g: https://m.youtube.com/watch?v=j_osu1WgGMU
There is also a nice technology connection video talking about braking lights for electric cars and in general, which can be dangerous.
As a first step, I would recommend checking out osm.org from a computer. Once logged in you can use it as an editor straight from the browser. The embedded documentation really helped me initially.
For edits whithin a page, I use inkscape. Both program combined have covered all my needs until now.