Hi Craig,
Welcome to the forum!!
Unfortunately the pinout for the Pi and Pico are very different:
However you could definitely make a custom adapter and use the 40-pin cable.
PS: Rob is working on this super cool Pico stacking project here: Stackable Raspberry Pi Pico dev system - #6 by Rob110829
(And I think there was someone doing similar in the Core tags on Instagram)
If you tell us a bit more about your project we might be able to help!
Liam
