[pocket]

Pretty sure you can choose to disable the secure boot options… from only the latest, to ones that were at one point trusted (old OSes), to no restrictions - https://support.apple.com/en-us/HT208330

[janoc]

You can - but it also apparently disables storage access. So you can boot Linux but not install it.

[ChrisSD]

Isn't that just a driver issue? Apple's T2 chip is a collection of customised hardware, no?

[rebane2001]

But if you really wanted to, you could still install a distro on USB I guess