The newer Macs with T2 chips do prevent you from installing Linux, actually.

There appears to be some debate online as to whether turning off secure boot on T2 Macs allows Linux to work. It should, but there are some reports online that it does not, at least if you want to use the computer's internal storage. https://www.reddit.com/r/linux/comments/a4thsc/the_actual_fu....

I would have expected this to be sorted out by now, but that doesn't appear to be the case. If anyone knows more, please share...