I tried to get the T480 added to the list, it’s by far the most cost-effective ThinkPad you can get at the moment, and it works flawlessly with QubesOS which is documented by more than 10 HCL reports.
It got rejected for no clear reason, which to me makes it seem like the feedback mechanic doesn’t work, or it works and there is no interest from the maintainers to expand the list.