The T2 chip is Apple silicon, and marked the beginning of really locking down the OS running on a Mac (as opposed to iOS, which was always locked down that way, and Intel Macs which of course could run anything).
It was the first mass market SoC hardware test of their new Mac chip design and it seems it was also to prep macOS for the M line. The level of control Apple gave it makes repair and refurbishing very difficult without Apple’s authorization.
That is an interesting point. I did mean the M series, M1 and later, when I said Apple Silicon, and that's usually how I interpret the phrase. The Wikipedia article by the same name seems to interpret it much more broadly, also including mobile stuff like the A series.
It was the first mass market SoC hardware test of their new Mac chip design and it seems it was also to prep macOS for the M line. The level of control Apple gave it makes repair and refurbishing very difficult without Apple’s authorization.
T2 Overview PDF https://www.apple.com/jp/mac/docs/Apple_T2_Security_Chip_Ove...