[OnACoffeeBreak]

They probably mean "on-board" instead of "on-chip".

Data sheet [0] section "5.4 Powerchain" shows an external RT6150 buck-boost switcher with an external inductor.

0: https://datasheets.raspberrypi.com/pico/pico-2-datasheet.pdf

Edit: reading further in that section of the data sheet, "The RP2350 has an on-chip switching regulator that powers the digital core at 1.1V (nominal) from the 3.3V supply, which is not shown in Figure 7."

It has proven difficult enough to find a PDF of the schematic (I don't have Cadence Allegro installed) that I am giving up.