That’s a cool idea. How do you get to the PCIe lanes?
I’ve been hoping thunderbolt would make GPU enclosures more of a thing, but they seem to still be bottlenecked by even that pretty good interface (last I checked, at least).
In the past, the thing to look for was laptops with multiple mini PCIe connectors (generally for WiFi cards and sometimes cellular) but now the thing to look for is M.2 slots with PCIe on them. Generally the easiest thing to do is to yank out the wifi card and add your own thing there, and then for networking you can just use either onboard or a decent type-c gigabit dongle. Some laptops have spots for multiple SSD's and you can just use one of those instead.
Keep in mind that even a basic PCIe card can pull up to 75 watts and that you'll probably need some sort of external power supply. There are two main routes you can go- use a second external laptop power brick, or what I did- slap an entire computer power supply in there.
I bought an SFX power supply from EVGA, who has an awesome B-stock program where you can get returned / refurbished stuff for cheaper than normal and it still comes with a warranty. If you do decide to use a computer PSU, I'd highly recommend one that's modular, because you won't need a bunch of the wires and they take up a lot of space quickly.
To tell the power supply to turn on, you can either use the 'paper clip trick' to jumper it on, or get an "ADD2PSU" board (basically a relay on a PCB) and use a USB cable to power the relay and you should be good to go.
If you use a laptop power supply, you'll either need something that's 12V or get step down boards or a Pico PSU or something like that.
The thing to search up is "M.2 NGFF to PCIe" or something like that. I'd recommend getting ones with some kind of cable and an open back of slot design so that you don't wind up needing two adapters for one thing.
Adapters and cables are available from the usual suspects- Amazon, eBay, and Aliexpress will all have what you want.
This is a lot of information, but this is legitimately pretty easy to do as long as you make sure you check all the boxes- PCI lanes, external power, and something to keep the new stuff you're strapping on safe.
I’ve been hoping thunderbolt would make GPU enclosures more of a thing, but they seem to still be bottlenecked by even that pretty good interface (last I checked, at least).