I have a MacBook Pro running Manjaro Linux, Audiophile Linux and the latest OS-X. There's no issue: there's a command that can toggle the security status. I think the instructions are even in the Apple documentation.
Now getting some of that configured to use the cheap hardware is a more complicated story.
Your experience matches mine. And UEFI is more capable if you're interested in a multiboot setup, preserving a recovery partition, and such-like. I've yet to see a UEFI machine where you couldn't shut off secure boot in its firmware/settings menu.
As someone who worked a couple of decades for a company selling GPL-ed development tools, I was always mystified by a similar case. It was the developers who wanted to develop proprietary software and were upset that they would have to pay subscriptions if they wanted to distribute their software without the GPL "restrictions".
The thing I saw with Pascal in the late 70's / early 80's was that in order to handle industrial use cases, each computer company invented its own dialect (I worked on one at Burroughs).
That was one of the problems Ada addressed. But its initial problem was the cost of compilation and builds on the hardware of the time. That got sorted out by the end of the 80's, but then other factors like contractors not wanting their customer telling them how to do their work came into play. Sort of a confusion of requirements and implementation methods.
Whoops, forgot. The borrow checking memory management is available on GNAT Community Edition 2020, for SPARK and (I believe) also Ada itself. The GNAT Ada compiler is used to compile and build SPARK apps. Since SPARK is very strict, the implementation is robust even at this relatively early stage.
There's a telegram group https://t.me/ada_lang you could open that question on. Also, there's work (I think on GitLab) on a package manager called Alire. And the very old standby comp.lang.ada which tends to have some interesting conversations.
This question almost always needs further qualification, to determine what the goal is. Learning to program is different from preparing for a new career. You get the drift.
That said, for "pure" learning to program, I like the DrRacket IDE and the course book "How to Design Programs" ( http://htdp.org/ ) because it teaches problem solving with programming. And that's what it's about. Should give a newb a sense of whether this is something they want to spend their time doing.
The concept are transferable to other languages; the specific language skills not so much.
Now getting some of that configured to use the cheap hardware is a more complicated story.