The USB fun never ends!!!
To boot using the hub ports (on sweetp, at least, but potato is probably the same), just blacklist the onboard_usb_hub module, either in /etc/modprobe.d or with a boot option
modprobe.blacklist=onboard_usb_hub
CAVEAT: this might have some other effects that I haven’t noticed (yet), but the one I’ve observed is that it eliminates the hub reset (?) and subsequent device reset that has made all save the OTG port unusable for a boot drive. I have had a USB keyboard in another hub port next to the thumb drive, and that’s not caused any issues, but testing has been minimal.