It all works now, I just needed to run rpiboot then rpiImager.
I did need to load the seeedstudio .img https://files.seeedstudio.com/wiki/ReTerminal/RPiOS_Images/2021-06-02-Raspbian-reTerminal/image_2021-06-02-Raspbian-reTerminal.zip, and avoid any official update.
Does seeedstudio have a more recent .img available after 2021-06-02?