So it seems the NanoPi R6S has some interesting on-going issues in #OpenBSD (from what reading I've done, not sure if it's still relevant), but the "wanted hardware" page on the OpenBSD site says Patrick is looking for a NanoPi R6C, which from what I can tell is the same thing as the R6S, minus a second 2.5 Gbps interface and with some additional connectivity (debug usb-c, which the R6S seems to lack probably due to space constraints (though the header appears to be present)).
At any rate, I ordered an ODROID H4 with the quad port net card addon to replace my current firewall and I now own a useless (to me) NanoPi R6S. I've contacted Patrick via email to see if a donation of the R6S would be welcome in place of the R6C he's requested. I think it would be, but I always like to ask =)
Will be shipping the R6S to Patrick in Germany soon. Glad my loss can benefit the OpenBSD community :)