Writing from a Carbon X1 6th gen right now. Ubuntu 18.04 stock, no tweaking required, all worked no problem. The best laptop I ever had.
Previously owned a 4th gen. 16.04, minor tweaking, also excellent laptop. Pricey, but the best you can get.
I’ve got one of these as well, and it’s great at running Linux, but it’s SOOO much slower than my 6-core MBP.
Compiling any project that takes longer than 30 seconds kicks the fans into high gear, throttles the cpu, and leaves it nearly unusable until it’s finished.
maybe this anti-throttling script[1] should help. I'm able to run at max CPU clock frequency at 85-90+ deg temps without throttling when doing CPU intense stuff (t480s, not carbon, but should work on carbon).