In a perfect world, there would be no documentation about how GPIO works on Raspberry Pi, but about how it works on Linux, and all drivers for all hardware which exposes GPIO pins would implement the same generic API, hence the same set of libraries would work on all hardware.
But RPi used to implement a lot of RPi-only APIs, based on closed source drivers, where everyone knew that this won't survive forever. But since there was no working alternative for RPis, the ecosystem with libraries and software like Node-RED plugins emerged around those closed source/vendor APIs. This does not only include GPIO, but GPU/video, camera, and more.
During the last years, the inevitable transition happened, and the RPi kernel migrated from a lot of those those RPi-only APIs and drivers to generic native Linux ones, affecting the GPIO libraries, RPi video => KMS/DRM, RPi camera => libcamera, etc. Since the ecosystem which develops all the software and higher-level libraries consists almost only of volunteers, which are not paid for their work by anyone, the required rework was too large for many, hence the projects died, or still exist but are functional only with workarounds or scattered hacks, or ancient distro versions necrod in Docker containers.
This was not a surprise, since all those APIs were deprecated a long time ago, but equal functionality not reached by native alternatives at the same time.
On the bright side: it can only become better. IMO important is that open source developers stop wasting time on these legacy RPi-only APIs, but switch to the existing sustainable alternatives. But this is easier said than practically done. But I am indeed surprised that there is literally no maintained Node-RED plugin which supports any of the modern GPIO libraries, while the legacy ones are still developed. IMO a waste of time, as hard as it is to accept that fact, when the consequence is to either require a major rework or archive the own project.
