This is a complete example on how to stream uploading with undici library.
Somehow following popular results from search are not complete, or lack of description of key secret.
nodejs/undici#2202
https://github.com/nodejs/undici/blob/main/docs/examples/README.md
https://gist.github.com/PaulMougel/7511372
This is my try. It is working with current node v22.13.0. And the key secret is actually the FormData provided by undici is broken in supporting streams.
https://github.com/liyu1981/undici_upload_example
https://gist.github.com/liyu1981/e85c9ace0e9304350fb3b5c13844062d