Feature request - RP2040 as both MCU and USB to serial adapter

Something I’ve been thinking about for a while now. Similar to USB to CAN adapter mode for RP2040. A firmware mode that uses the RP2040 board as a klipper MCU, but also uses it to create one or more extra USB serial devices alongside it, which relay their RX/TX signals via chosen pins to allow you to piggyback another MCU (or more) from a single USB connection.

Here is an example of such a thing being done as standalone firmware: GitHub - Noltari/pico-uart-bridge: Raspberry Pi Pico UART-USB bridge

That one only has two added devices, but there are forks of that going up to 6 (using the RP2040 PIOs). The extra connections show up as linux serial devices and can be treated independently. As seen here with one I am using, which has been working well so far:

But that requires a dedicated board to act as the adapter. Being able to let it do both jobs would be great.

I wish I could try and implement this myself, but I am not familiar enough with the klipper MCU side nor low-level details of USB to have any hope of doing so.

Thanks for reading.