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.
For my personal devices:
I’ve worked with work systems that used RedHat and Ubuntu back in the late 2000’s, plus decades of work computers with Windows. But I’m no longer in a technical career field so I haven’t kept on top of the latest and greatest.