It seems as if you could get a range of voltages at the point between C1 and C2 with a closed negative feedback loop that controls the duty cycle of the flying capacitor.

If you charge the bottom cap more and the top one less, you can jack the voltage toward the power rail.

A buck as well as boost-buck converter could be produced without inductors.

Indeeed, I found an article about exactly this: https://www.allaboutcircuits.com/technical-articles/boosting...

The article references the LTC3265 IC, whose datasheet says "The LDO output voltages can be adjusted using external resistor dividers" (connected to the ADJ pins).