Add implementations - but the PRs seems to be pending for very long

I would like to have the [zephyr coap](https://docs.zephyrproject.org/latest/connectivity/networking/api/coap.html) implementation added to the C section. But to be frank, for me this seems to be not working creating PRs, they last for years without visible processing or feedback.

So:
Are  PR with new implementations really welcome?