Apple Blocks GNU/Linux From Booting On New Hardware With T2 Security Chip

GNU/Linux cannot see the built-in storage at all even if secure boot is disabled.

GNU/Linux can boot from an external Thunderbolt drive. This is not a big deal with a desktop computer such as the Mini. On a laptop (the new Air), it could be a big inconvenience.

Good to know: since the built-in storage is incapacitated on a non-Apple-approved OS, there's no sense to get any bigger than 128 GB.

https://support.apple.com/en-us/HT208330

https://www.apple.com/mac/docs/Apple_T2_Security_Chip_Overview.pdf

https://www.omgubuntu.co.uk/2018/11/apple-t2-chip-cant-boot-linux

##EDIT##
Illustration. Sun Sparcstation: stack them up. With the new Mini, old times, better times (?), come to mind.