Linux hardware vendor and creator of the Pop!_OS distribution, System76, have made their own desktop for a while now but they're moving onto a custom laptop next. Something they've been planning for some time, as they've gradually scaled up their in-house manufacturing.
On Mastodon, System76 Founder and CEO Carl Richell, showed off two photos of the panel for the LCD:
“Virgo” is the code name for the laptop we’ll manufacture at our Denver factory. This is the LCD “A” panel milled from thin 6061 aluminum bar stock.
There wouldn't be an ODM or OEM involved in this case but some outside suppliers would make parts for us that we design. We don't have SMT machines for PCBs for instance but we do the EE work. We have laser, mills, brakes, 3D printing, paint, fastener machines and other machines and techniques in the Denver factory. There's a video on our desktops page that shows some of them. https://system76.com/desktops