GSoC had one project that went in this direction but ther weren’t any updates lately:
Then there is jfranmatheu on Twitter who is apparently creating a menu customizer of sorts (?)
Don’t know what the final ting is going to be but he occasionally posts updates that look like it could go in the direction you are seeking.
For the record: I was also hoping for Blender to get native cutomizable menus with the GSoC project as I see custom menus as a major way to speed up workflow on a very individual basis.