E6430 Yes has HDMI port (Full Size) Socketed CPU, Easiest to build with. E6530 Yes has HDMI port (Full Size) Socketed CPU, Often has better dedicated GPU. E6230 No (Mini-HDMI) Soldered Very tiny motherboard. E6330 No (Mini-HDMI) Soldered Middle ground size.

Socketed CPUs: These are the only two in the range where the processor isn't permanent. You can take out the i5 and drop in a Quad-Core i7 later.

The E6...30 series has a power button and HDMI, so don't need a keyboard like x230

You can just buy "E6430 Motherboard", you don't need the computer.

Elitebook 8470p also has socketed CPU, so you can put a quad core i7 (x230 is dual core, but therefore cooler), and some Elitebooks come with dedicated AMD graphics (x230 uses Intel integrated graphics). Elitebook can have Quad-Core i7-3630QM, whereas x230 can have Dual-Core i7-3520M, as their max CPUs. Both have 16gb ram. Thei7-3740QM has a passmark of 5600, whereas the i7-3520M is 2900.

Elitebook 2570p also you can put in the quad core i7.

Wood

The Grounding Trick: Laptops use the metal "shielding" inside the plastic case for grounding. In a wood case, you just need to ensure the motherboard is mounted on brass standoffs (the little gold screws).

Powerbank

Yes but because the X230 is a laptop and not a phone, you can't just use any cheap power bank from a gas station. You need one that meets the "65W PD" standard. A 20,000mAh bank will give you roughly 2 to 4 hours of run time.

HDMI Screen or connect with VGA (x230 has VGA and displayport mini but without audio). x230 supports up to 2 external monitors if you use a docking station, or 1 external if using the side port.

Mini DisplayPort to HDMI Adapter

Pixel8 as a monitor

Pixel 8 is the first Pixel with DisplayPort Output hardware.

Since your Windows 7 motherboard (like the Dell E6430) is spitting out a standard HDMI signal, you can "trick" your Pixel 8 into thinking that signal is a webcam or video feed, using an HDMI to USB-C Video Capture Card. Open an app on your Pixel called "USB Camera" or "nExt Camera" (available on the Play Store). You can also use Spacedesk (wireless, if the x230 has wifi), by installing it on the x230 and the Pixel8, but Spacedesk isn't foss, isn't encrypted, and creates a hole in the Windows Firewall.