My laptop uses an LVDS internal panel, if I’m not mistaken, and the display signal is routed through the iGPU via NVIDIA Optimus rather than a direct dGPU output. That said, I mostly run it with an external monitor over DisplayPort.
I rarely game on the internal display while mobile - in those cases, it’s mainly used for productivity work.
With my previous Quadro RTX 3000, I didn’t notice any significant LVDS or Optimus-related bottleneck. Performance was nearly identical between the internal panel and the external monitor. In any case, now that I’ve installed the new card, I’ll see how it behaves in real-world use.