Universal Android Diag Enabler Extra Quality Download ((better)) ⇒ <Confirmed>

You should see: "Diag port enabled on ttyUSB0" or "DM_PORT activated"

Some manufacturers allow access through the phone's dialer without root: universal android diag enabler extra quality download

Works across multiple Android versions (from Android 9 to 14). You should see: "Diag port enabled on ttyUSB0"