Hi,
Persist Variables 100-114 are used for KFLOP->PC communication and Spindle CSS variables. Other than those it is only the Variables you configured in KMotionCNC | Tool Setup or otherwise used by your C Programs.
Distance to go will be difficult to implement as the Trajectory Planner is buffering potentially hundreds of blocks ahead and executing hundreds of blocks per second with blocks blended, eliminated, subdivided, rounded, etc. If the machine is very slow and mainly doing simple straight lines I suppose it could be useful.