... are in a way possible. By looking what is possible i created a little proof of concept, which means that the web site linked below is not guaranteed to work for any other browsers than Firefox and Chrome. It has been created in one day so it is really unpolished / lacking features (maps to click on, search, etc.).
glitch.djangoserver.de allows you to create a route and creates a bookmarklet which you will have to drag to your bookmark bar or bookmark in any other way. The first click on it will set the first waypoint, the second click will select the second one and so on... If anything goes wrong there is a reset bookmarklet.
Hoping for feedback,
BuzzDee