OK, that's better than nothing. PCIe support will be necessary for my use case as the logic nodes will get attached to the backplane via U.2 / PCIe connector, and the storage nodes will use this connector to talk to the SSDs.

It is possible to get usb and I am happy to share how it can be done. However,  it is a hack that never will end up on github. 

Why shouldn't you publish your "hack" on Github? Just because it's not fit for production use yet?