ESP32-C3: GPIO 20/21 useable?

[DrMickeyLauer]

I‘m always using the native USB pins w/ multiplexed UART+JTAG. Can I then repurpose the GPIOs 20 and 21?
Also: How does the bootloader know which output to send the debug logs to? Or do they always
appear on both the devel board UART and the native one? If so, can I change this?

[Sprite]

Yes, you can, but be aware that afaik there's no way to get debug prints only on the USB-serial-JTAG, so you need to be OK with either no debug printout or some chatter on the TxD pin.