Yes ! Sidewalks and crosswalks will be the next step. I noticed that the crosswalks don't follow the road curve, so I need to make a planar projection for them. Sidewaks will be a road with extrusion, and by extension we can create central reservation.
I also have to create some tags to set some properties of the roads, like its width, for now it's a default value for all the roads.
I think I will make generator of preset splines, or an other way to configure the road properties, actually it looks like this picture, the splines points have to be in a very specific positions, and the points selection may be a bit complex to use. An overlay userfriendly may be the solution but I am not very good on UX/UI.
How we actually customize the lines : (by default, border lines are full, lines between two roads are dotted)
I will reproduce some other real life example to see what is missing.