[AlotOfReading]

For context, I also work in the industry and have seen embedded codebases ranging from several thousand lines up to tens of millions.

The region where A is true for me is roughly about an 8051 whose entire codebase could be held in a single developer's mind at one time. That's an increasingly miniscule portion of the industry for many good reasons.

For B, my experience is that your codebase often long outlives the products and hardware it's shipping on and is doing very nontrivial things like wireless networking. The article is saying you should have a way to run the code without hardware (obviously useful for testing/CI/bring up) and with a HAL (which makes porting easier), among other common sense suggestions. Vendors don't always provide this, but my info might be out of date because I haven't been able to work in this space for some years due to my salary expectations.

If you have a full RTOS (e.g. FreeRTOS, RTEMS, etc) you definitely do not get the ability to do these things for free. You need to actually have an architecture and work to keep things like raw hardware accesses isolated. I've spent literal years of my life cleaning up codebases where this wasn't done, so I have strong opinions on the matter.

[contingencies]

We seem to be essentially in agreement, although I would say A is technically most products (both new, and ever produced) one might qualify that by saying they're likely not the sort of thing you would see volume on in a western embedded career. I think the other comment regarding scale being absent from the article hits the nail on the head.