So items 1 and 4 are courses which you need to sign up for and get everything including instruction. That fails to qualify as "on their own".
Item 2 is documentation. This is good! But without access to the system to try it out, how self-teachable is it?
Item 3 is the one counter point. With a third party emulator though, how comprehensive/accurate is it? Would you hire someone to work on a mainframe who'd never used a real system before?
Compare that to e.g. Java. Sure there are plenty of college courses, some even Oracle affiliated, but I can also just download a Java compiler and start plugging away. .NET is there with Visual Studio Express. Oracle cloud, for everything else wrong with Oracle, has a free tier with no time limit. Microcontrollers for embedded development can be had for €20. You can install Linux or a Linux VM on your own computer. Even stuff that falls into the more enterprisey camp like MS SQL or Oracle DB has free personal licenses.
>So items 1 and 4 are courses which you need to sign up for and get everything including instruction. That fails to qualify as "on their own".
Attending a course on your Own.
>Item 2
No it's a MVS distribution (a full blown Operating System) with all the compilers 99% the same as a "modern" z/os
>Item 3
That's the S/390 emulator.
>Would you hire someone to work on a mainframe who'd never used a real system before?
Most Mainframe-Programmer where never near the Hardware anyway...so YES i would do that absolutely (you don't do Hardware near programming in Mainframes, an emulator is perfectly fine), same as a Dev who programs in a VirtualBox, no difference.
If you want to learn how to use it, and MUCH more:
WHAT?
https://www.ibm.com/it-infrastructure/z/education/master-the...
http://wotho.ethz.ch/tk4-/
https://sdl-hercules-390.github.io/html/
https://mainframe.informatik.uni-leipzig.de/
>There's a difference between "unable" and "unwilling".
True words, look at the Links.