Note that it is Ubuntu etc certifying the laptops. You can't buy the laptops with the certified version of Linux on them, and for the model I own (T430s) the only version they list (11.10) is end of lifed in ~3 weeks. However Linux is likely to just work on Lenovo Thinkpads, although binary drivers may be problem if you pick an Nvidia GPU.

I'm also a member of the Thinkpad faithful. Other than screen resolution (grrr) and bezel size, they are delightful machines. It is trivial to change/update much of the hardware - they don't solder memory down, nor SSD drives. And Linux works perfectly - the only thing it doesn't support is the fingerprint reader which ironically is made by a company Apple bought not too long ago.