Can I use TrimSheetFast with Blender?

Yes. Many Blender artists model and unwrap their assets in Blender, then use TrimSheetFast to generate trim sheet atlas families for those assets. Build your trim sheet template, define marker regions, generate atlas outputs and PBR maps, then plug the exported PNG maps back into your Blender materials. That keeps Blender in the modeling and UV stage while TrimSheetFast handles the faster repeated atlas generation pass.