The particular stepper motor driver is: https://www.amazon.com/dp/B081DKSRB5?psc=1&ref=ppx_yo2ov_dt_b_product_details

Based on the little metal bar joining the j2 pins, it appears to have came pre-soldered as UART.

drivers just output HIGH to every output pin from the moment they get VIO & GND

that's normal, that's how you hold a motor still

The issue is that despite all 4 output pins being high, the motor isn't being powered. It's as loose as when it's unplugged. I tried swapping the cables around in case the wires were mislabeled on the Nema17s (https://www.amazon.com/dp/B07KW7F3P9?psc=1&ref=ppx_yo2ov_dt_b_product_details ) but it didn't solve the issue. I tried adjusting the Vref of the potentiometer to no avail either.

-Edit: That was when using my 5V 1.5A power supply module. It's able to power the motor when directly plugged into it, but through the TMC2208 nothing happens. I have a spliced phone charging cable that gets 6V 2.5A and it does lock up the motor, but fails to drive the motor all the same. I'll swap back to it for testing. Perhaps I should get a 12V 3A DC supply adapter with a female connector and see if it just needs more power?