Gradually increase DC voltage boost over time
Forget about using a digital potmeter, it's too complex.

How a voltage regulator usally works is that it uses a fixed reference voltage and compares that to a fixed (for constant output voltage) or variable (variable output voltage) feedback voltage.

You're thinking about changing the feedback with a digital potmeter. That's complex to implement.

What is much easier is to use a fixed feedback voltage divider, for example 10:1 and compare that to a variable reference voltage.

You can make such a reference voltage by using the DAC. Or when using a micro controller, one of the PWM outputs. You need to filter that PWM signal with some RC filter stages so that at the output of the filter you get a variable (and digitally controllable) voltage of for example 0 to 5 V.

The regulator feedback loop then multiplies that variable reference voltage by a factor 10: and presto 0 to 50 V output voltage range.

Have a look here which discusses a Chinese "B3603" digitally controlled DCDC converter which uses the principle I explained.

If you do not need the digital control you could also just use a sawtooth generator circuit to generate a 2 - 5 V sawtooth, then use that as the reference voltage for the regulator circuit to multiply that to 20 - 50 V for example.