Not exactly what you meant but Coraid did implement a something like this
that had 9p on it. Sort of. It was an ARM based PCIe card spoke 9p over
something like IL without the IP (bwc called it EL) using network ports on
Sometimes they appear on ebay as "coraid mass storage NIC" or some such.
Not the repurposed SuperMicro Cards but something that looks mor
complicated with a SO-DIMM socket on it.
The ARM CPU was also used for other services running on/for the platform
that were performed by the card. The card could be powered by POE so the
chassis could be powered down and the card could still be accessed. The
firmware on the card was, IIRC, not quite plan9 but constructed mostly from