Hello! Just an FYI: as requested by @happy-kitchen-89482, I opened an issue for Cython Support (https://github.com/pantsbuild/pants/issues/14752), I also created a repo for showcasing what I've done so far (https://github.com/houtenjack/pants-cython-minimal-example). Feel free to fork it if you are interested or have some inputs!

Thank you!