I have a 5th gen X1 Carbon. Great machine in every aspect but RAM, and runs Linux flawlessly. It has 8GB RAM, which is more than enough for Linux plus developer

I have a 5th gen X1 Carbon. Great machine in every aspect but RAM, and runs Linux flawlessly. It has 8GB RAM, which is more than enough for Linux plus developer containers, but not quite enough for running VMs; and it is soldered to the motherboard and thus non-upgradeable. My setup cost ~1.5k€ (base setup plus larger NVRAM, better screen) although if you add touch screen, 3G and other bells and whistles you get to 3k€ pretty fast. I wouldn't add any hard requirement over the base machine.