This entry in the documentation suggests that there is support for deep sleep in the current MicroPython release. However, as far as I can see there isn't? At least, there doesn't seem to be a machine.DEEPSLEEP_RESET present in the current build.

Looking at https://ghubcoder.github.io/posts/deep-sleeping-the-pico-micropython/ it looks like adding this capability to the rp2 port is fairly easy, and there is an out of date — and looks to be unmaintained — fork at https://github.com/ghubcoder/micropython-pico-deepsleep.

Any plans to add support for DEEP SLEEP to the RP2 machine class?