There are adjustable linear regulators whose voltage set pins do not work via feedback from the output. These often allow setting the voltage down to 0V, and often just use a single resistor to set the output, so a digital pot might work very well for those. For example, look at the LT3045. The SET pin sources a 100uA current, and you set the voltage by connecting it through a resistor to ground. The resistor value is simply the desired voltage x 10000, e.g. 33kohms for 3.3V.
(Is there anything I’m not thinking of here?
Also, for regulators with traditional FB pins, an option to control output voltage is to inject voltage into the feedback node. TI has a downloadable tool called Power Stage Designer that includes a handy calculator for this, and I’ve successfully used it. You choose some variables (like some of the resistor values, to set your quiescent current through the divider), and then give it the feedback voltage, the output voltage range, and your control voltage range, and it spits out the remaining resistor values. It’s also got the ability to calculate values for digital inputs, so if you happen to have enough unused GPIOs, you can dispense with a DAC altogether.
https://www.ti.com/tool/POWERSTAGE-DESIGNER