I checked out the Uno Q’s schematic. The STM32U585 SWD interface is connected to the Qualcomm SOC through level shifters. SWDIO is PA13 on the STM, GPIOI25 on the Qualcomm and SWCLK is PA14 on the STM and GPIO26 on the Qualcomm.
This makes sense- when you flash the STM32U585 from the Arduino IDE V2.3.6, it does so via USB, and the Uno Q’s USB port is connected to the Qualcomm SOC. Same thing would occur when you program the STM via App Lab.
There is already a direct UART link between the Qualcomm SOC and the STM (via level shifters) - shown on the schematic. But, I think that is a part of the Bridge (although there are other interconnected ports that I believe also participate in the Bridge transactions)
The Uno Q schematic link is here:
hope this helps- cheers