When they say modules, does that mean mainboards?

They mean each part. Here’s their store for individual parts.

This announcement includes a new display, so anyone with the old display can swap out their old one for the new one. People can swap out batteries. Keyboards. Touchpads. It’s a modular design so that each module can be swapped out if broken, or if there’s been an upgrade the user wants.

I wonder if research into sonic boom physics could translate over to high speed aerodynamics generally, to include the useful models for high speed trains.