Hello, all.
In order to provide closure for this topic, OT RCP support on K32W0 USB dongle is available as a binary in the K32W0 SDK starting with version 2.6.10. The binary can be found in /tools/wireless/ot-rcp folder under the ot-rcp-uart-no-fc-usb name, as binary and axf file. You can find the latest SDK by accessing this link .
Looking forward for your confirmation of the example working.
BR,
Mihai
I forgot to mention that otbr-agent needs an extra argument, please see this comment also.