To use your external monitor with your Surface device. You need the Prime OS 4.19 kernel because version 2 kernels 5+ don't have the external monitor support. I don't know why it's not supported it's just not. This kernel should work with any distro not just Prime OS and the WiFi is better. The kernel is available for download in the Resources section on this site.
I updated android.cfg with disabling power saving and compression features of i915 drm driver. I also added another menuentry for a tablet feature and a tablet that is being charged. You'll notice that the graphics are better for all menuentries except the tablet menuentry. Cheers.