For example, the microphone of the X1 Carbon 7th generation still doesn't work out of the box. You need to blacklist a handful of kernel modules and edit your PulseAudio configuration to force the loading of an ALSA source hooked to the correct device ID.
The Arch wiki has an article cataloguing issues and workarounds (with various degrees of success) for every generation of the X1.
But honestly, just buy a Thinkpad and everything works out of the box. Yes, everything.