Uconsole R-01 bootloader

Hi,

I am wondering if it is possible to choose to boot from an sd card plugged into the usb-a slot, for example to boot a separate linux distro. I have the R-01 but I would prefer to not use ubuntu in my own unsupported setup . Its better if i do not have to install the embedded versions of the OS onto the sd card in the slot. I want to plug in a second sd card and perform standard installs.