While Godot Engine 4.0 will come with Vulkan API support, it's also bringing in a ton of new advanced rendering options to make it a more enticing target for bigger titles and capable of making more beautiful games.
Godot 3.2 actually has a lightmapper, however it's a very simple one and it's both limited in features and has performance issues associated with it. With Godot 4.0, they're bringing in a brand new GPU-based lightmapper that is written mostly with Compute Shaders so Vulkan will be doing most of the heavy lifting. Although there's a CPU backup if a GPU doesn't support it. They're also planning to backport it to Godot 3.2 somehow too.
For the Godot Engine 4.0 system they have a few main goals including: maximum possible quality, ease of use, dynamic and static lights, proper seam-blending and lots of other advanced features like an AI-based denoiser on the final bake, to ensure lightmaps are as smooth as possible. The ease of use sounds good, enabling more developers to use it with good defaults and allowing adjustments easily in the Godot UI.
It's sounding ever more that the free and open source game engine, Godot Engine, is going to be a big force in game development after 4.0 is released. The blog post on their new modernized lightmapper can be read here.
Godot Engine 4.0 is due later this year. For more info see the official site.
In other Godot Engine news, Godot 3.2.2 is closing in on a release with a second beta build going up late last week. One of the bigger features there is support for 2D batching in the GLES2 renderer to improve performance.