How to dynamically adjust voltage divider (90V) using a 3.3v microcontroller
If you have a bit more detail about your feedback circuit (where the pot wiper goes) that would be helpful, as well as the resistance values used for the pot and its load resistor.

I'm thinking an optoisolator like this one: https://www.digikey.com/product-detail/en/on-semiconductor/H11G1SM/H11G1SM-ND/1793958 could be used to modify the voltage divider feedback using low-voltage drive. You'd drive the LED side with a filtered PWM signal to vary its resistance, or you could use a DAC.

If the feedback works the way I think it does, using a voltage-controlled current sink on the low side would provide a way to change the voltage too. You'd use your digital pot to control it, and have the current-sink open-collector or drain go to the main voltage divider.