The closed-loop drive is to feedback the rotation angle of the stepping motor to the control panel, compare the distance that needs to be rotated with the distance of the actual rotation, calculate the error value, and then compensate, so as to prevent the problem of multi-step and lost step. The closed-loop drive can completely overcome the lost step of the open-loop stepping motor, and can also significantly improve the performance of the motor at high speed
Question is how you should signal about it to the Marlin without patches. Current Marlin implementation looks heavy TMC based.
Does current pololu adapter have enough pins?
garkin
commented
3 years ago 
It should be not hard to implement using encoder.
Question is how you should signal about it to the Marlin without patches. Current Marlin implementation looks heavy TMC based. Does current pololu adapter have enough pins?
marlin docs marlin repo duet wiki TMC2209 datasheet TMC2130 datasheet
Also opens up Sensorless Probing.