Grayscale engraving, not a image. Inkscape drawed

2 options if both the vector and raster components are important for you:

1. create a raster version of the image and then bring both the raster and vector images into LightBurn.
2. bring raster into LightBurn, then trace the image

Use of vectors only for shape data and layer assignment is fairly fundamental to how LightBurn is designed so don’t see that easily changing. You could make a request in the Feature Request site if you wanted to explore it.