~/src/px4-firmwarefolder. The tilde represents the current user's home folder within the file system. You can also browse to this location with the file manager.
.elffiles in the
~/src/px4-firmware/build/nxp_fmuk66-v3_defaultfolder. We will later come back to building your own firmware binaries, when we set up an IDE (integrated development environment) to do it for us.