No idea, the IPQ40XX are supposed to have 2.5GN-BASE-T support though. So maybe there will be a small update in the future and it will make sense then. As for RGMII: the MR33 uses a "good old" AR8035 single-phy which is connected with RGMII. But again, it's neither here or there:
They could, if the device was honest about the built-in switch and would disable the vlan stuff. I had this patch for a while:
This worked reasonably well, it will also allows you to remap the WAN/LAN ports to your heart's content . But it was never accepted, because John is preparing a "new" DSA based switch driver someday that will do away with all of it... or not.
In a way, I had the dumb luck that quirks/hacks where easy to "hide" or already established code.
But in your case, you should ask around what the preferred method could look like. Otherwise, you could be stuck in review hell.