Webbuilder: blocks second uart on rp2040 / SKR pico?

[letrow]

For my 2-axes laser (under design) I use an SKR Pico (RP2040) that I want to control from the UART0 port on pins gp0 and gp1. The other UART of the RP2040 is wired to the TMC2209 chips.
By default grblhal sets the hal.stream to the native USB. Sending 0x8b to uart0 gives me control on that port which is exectly what I want. But this "0x8b claim" is not understood by UGS which only does a $I and fails to connect because there's no reply of course. Issueing the 0x8b manually fixes that but is clumsy.

So I wanted the uart0 to be the default "sender" port: In the webbuilder I selected "(virtual) UART" under "connection". The webbuilder doesn't agree with that saying: "2 uarts needed, only 1 available" (or similar).

Question: Is there another way of swapping the uart and native USB ports? (or is the webbuilder mistaken?)