Does Apple fear Linux / Android that much

It's about security. If you boot from an external device, they still want to make sure that your data is as secure as possible. A little while ago, if you installed macOS on an USB drive and booted the computer from there, you could gain access to all local data...

 

Is this now about installing or actually booting from USB? Because you should be able to boot from an existing drive without any checks if you disabled the settings. Otherwise it will only allow you to boot from certified OSes.

There you go: https://appleinsider.com/articles/19/01/15/how-to-make-new-t2-secured-macs-boot-from-external-drives

And one more: https://www.idownloadblog.com/2018/11/06/mac-t2chip-linux/

EDIT: And that's it, really. https://support.apple.com/en-us/HT208330

 

Theoretically it should work if it was set to no security, but I could never get Ubuntu to boot off of an external drive on my iMac Pro...it works perfectly fine on my older MacBook Pro.

 

With the coming of the t2/t3 "secure enclave" b.s., those who "want Linux" are probably going to have to resort to economical "build-'em yourself" boxes on which to run it.

Android?
You can run that on the Mac now with the NOX app player...

 

I don’t think this is true.

There is specifically an option to disable boot security. This article references the same thing: https://www.omgubuntu.co.uk/2018/11/apple-t2-chip-cant-boot-linux

 

Are you sure it's because of the security, and not an EFI issue?

 

There is no fear by Apple.

 

For me, this is simply evidence that Apple is conditioning users for a future where Macs are locked down to Apple’s OS and other OSes are nonexistent. I fully expect this to happen when Apple transitions to ARM.

The shift to services (especially user-targeted ad-based revenue) in technology will mean that tech companies will try to lock users user onto a single platform—Google, MS, or Apple, each with its own App Store and approved apps. Google may have the upper hand here as it’s apps and search engine are cross-platform.