It's not meant to, but the Pico board comes with 8MiB of flash, so it is at least conceivable, even if not sensible, that someone gets Linux to run there (with a healthy dose of execute-in-place trickery).
But why? It (well, the Pico board at least) already runs Python ;^)
The Pico comes with 2MB of flash rather than 8MB, but same idea, more or less. There are some 3rd party boards with 8MB. I suppose you could connect up an SD card via SPI for near-unlimited storage.
But why? It (well, the Pico board at least) already runs Python ;^)