I've used an older version of Sketchup (2017) to get some things into the game. You can export .dae files from Sketchup, then import them into Blender (I use Blender 2.79 as I'm slightly more familiar with it as many of the PC TMTK tutorials used it...). In Blender you assign textures and create the LOD's, then export as an .fbx file which the TMTK uses to create an object usable in the game.
For simple items like signs I'd recommend using the tutorials made by MsRedNebula (
https://www.youtube.com/playlist?list=PLshuUOVf3Xgo120YncVf2zLascxojnAXY ), she shows how to create simple things in Blender and get them ready for import into the game. Once you learn that then you can move on to importing more complex SketchUp models. I still don't understand Blender enough to actually model much in it, other than simple objects I am much more familiar with SketchUp, and even there I'm no expert.
It really comes down to trail and error learning Blender enough to use it to bring your SU models into the game, but it can be done.