So I had partial success! I was able to take the Pi-0 W fraumbuesa and boot the OS on screen with a standalone Pi-0 W. The only problem is, when I try to boot the Pi+PXFMini combo, it doesn't boot. Is the board damaged or did I solder incorrectly? Is it possible the cape itself is damaged? The Activity LED doesn't light up on the combo either. I'll be soldering pins onto the standalone Pi-0 W today to see if the cape works on it, wish me luck!
Edit: Problem is not Cape, the Pi that I had it attached to wouldn't boot off the SD, maybe I damaged the board during soldering? Anywho, taking a second, more careful crack at it today. Thanks for all your help Lander!