I guess the crux of my problem is trying to keep the efficient AMD card as the main render device and using the Nvidia card as needed. I'm just trying to posit solutions without knowing what is and isn't possible. Really, I'll follow any line of thought as long as it leads to a reasonable solution.
udev looks like it might be a possible solution, but I'll have to do a bunch of reading.
In the mean time I've swapped to using the Nvidia card as my primary by changing my BIOS from Hybrid to Dedicated, so I can use a monitor as a second screen, but it brings up an issue I had before where the UI scale of certain elements are far too big. To the point of cutting off / overlapping on the monitor. Elements inside of windows appear to be the proper scale though.
xrandr | grep -w connected
HDMI-0 connected 1920x1080+334+0 (normal left inverted right x axis y axis) 480mm x 270mm
DP-4 connected primary 2560x1600+0+1080 (normal left inverted right x axis y axis) 344mm x 215mm
