I recently picked up a Dell latitude 7300 for less than $300usd. It has two sodimm slots (supports 32gb) and up to 1TB SSD. I’m pretty happy with it although it’s a touch older than the x1 carbon gen8. The 7400 is slightly larger with a 14” display and is the same generation otherwise.
I’m running Linux mint on it and haven’t tried your specific distro.
Thank you for pointing this out. I never noticed before, but also couldn’t figure out why I’d struggle so much to find what I was looking for when I signed into proton. This explains it.