Another update:

I ordered a serial to usb cable from Amazon and made my own shoestring-style USB2EQ5 cable. I still have my Lubuntu OS running on the Raspberry Pi. Everything connected just fine. No issues I could see (Other than my lack of knowledge in actually operating Kstars/Ekos).

Telescope control was as expected, I could slew the scope around with Kstars or manually with the scope control window. I could lock back on the Sun (I'm indoors, was just making sure it all worked) and sync and track it.

Some day I'd love to figure out why the bluetooth dongle can't connect on the RPI, that will probably drive me insane. Seriously.

But for now, I'll deal with one additional cable on the mount and consider this a win. Now to learn how to actually use Kstars to do my imaging :)

Thanks to everyone who helped, if anyone ever comes up with additional info or suggestions on getting the BT2EQ5 working I'd love to hear it. I'm off to Kstars school in the meantime!