In the past month, the team has been hard at work introducing the new native extensions system for Godot 4.0. GDExtension is a new implementation of the GDNative layer that allows the creation of compiled plugins for the engine. At its core, GDExtension is a C API that enables registration of classes implemented within a dynamic library. This allows dynamic libraries to be used by Godot in a way that is much better integrated then its predecessor, GDNative. Together with the godot-cpp library, GDExtension introduces a system that allows extending Godot to nearly the same level as statically linked C++ modules can.
The new registration system is now part of Godot's ClassDB. This means that classes implemented in plugins are indistinguishable from core classes.
Help pages are automatically made available for your classes, detailing their properties, methods, signals, etc.: We're still working on the ability to also add descriptions to each.