Oh wait... Hang on one cotton-pickin minute...
When in the bootloader my device is not seen as an adb device, but is seen as a fastboot device.
Finished! I just needed an old usb-c 2.0 cable and it looks like I was asking the wrong questions. When in the bootlader the phone isn't an adb device, it's a fastboot device, so searching for adb devices won't turn anything up anyway... All this time I was just asking the wrong questions.
I'm gonna update my earlier post from last year where I didn't tell myself what was going on. Sorry for the spam.