The Google Pixelbook has an Assistant key where the Win key usually is. It sends the 0x58 scancode that we didn't interpret as anything at all.
The search key (capslock) is left meta already, so let's interpret this as right meta I guess.
I don't think that Assistant key should be mapped to KEY_RIGHTMETA for following reasons:
IMO we can add all 12 KEY_FN_FX evdev events as e0 variation of the ordinary or FX keys