When attempting to build micropython for rp2040 in a windows environment, the make/cmake environment generates a command line that exceeds the windows10/cmd.exe line length limit of 8191 characters.
This is because the RP2 SDK requires about 3k worth of C include paths, and the list of files compiled that is generated on a single command line is about 6k (depending on exact path names.)

Extensive discussion and whining here: https://www.raspberrypi.org/forums/viewtopic.php?f=144&t=306333

I'll add that compiling all the C files for micropython with a single command line seems ... dangerously likely not to scale well on other build platforms as well.