I am a bit confused… why Arduino shield? Since this board has almost everything, I think this board itself can be an Arduino-compatible board with the onboard ESP32. As an added benefit, MicroPython can also be used.
The groves and LEDs position is OK but when you stack a shield on the top of this board, LEDs will not be visible and grove cables may come in between them. May be repositioning them near the edges would be better.