obj to sldasm conversion is doable in the sense that it is possible to import and use 3D OBJ files in SolidWorks for making new parts that can be then added and saved as of assembly files (.sldasm). You can find numerous and guides about SolidWorks and how to do exactly this on the Internet.
Direct conversion might be possible, but what the converter will do is to convert the simple OBJ file to a SolidWorks part that will be put into the assembly container.
Updated: November 2, 2023