avivgr

from the platform io package manifest http://dl.platformio.org/packages/manifest.json looks like the 'toolchain-gd32v' toolchain supports windows and linux only. However, from this commit: https://github.com/sipeed/platform-gd32v/commit/55ee76d056cd975b4b03c27b97f98f1ec271b996#diff-478ad51182f8482ddadda85fda7a9c38 Maybe the 'toolchain-riscv' toolchain can be used instead?...

not possible. This code is very t2.0 specific, and does not interface to any sensor.

Code is licensed under BSD license, use it as you please. teensy 4 has different hw which will require rewriting the low level usb code.