Built for Godot 4.2, support for other versions not tested
To install, drop the better-path3d-gizmos folder into the addons/ dir of your Godot project. Then, in your project settings enable the BetterPath3DHandles plugin.
The built-in Godot Path3D gizmos don't allow for per-component editing. This gizmo adds separate X, Y and Z handles to each point in the Path3D's curve. It's a very rough plugin, I got it to a functional state and called it that. It's unpolished, and I hope it gets obsoleted soon in favour of an out-of-the-box gizmo improvement in core.
Example 6-point Path3D without this plugin:
And with the plugin:
