When I was actively hacking my chromebook, there was tons of advice like this, and 90% of it didn't work on both arm and intel-based chromebooks, and the advice-givers never mentioned which category it worked on. Sometimes it was buried 5 paragraphs into the webpage you were sent to for downloads, sometimes not.

Has any of this changed?

Also, I tend to take with a grain of salt any comment that starts with "it's easy/simple/obvious", especially if it doesn't provide details or a link.

I was talking about a specific device on a specific dimension brought up by the GP, i.e., "freedom to tinker for the owner while preserving security for the masses." Whether that became a standardized process is a different story. By and large it has changed across models, but nevertheless it was a good balance of ownership/hackability without compromising security that can be emulated by other devices if they choose to.

There's no specific device under discussion. Where do you want the link to go? Google?