Not quibbling at all, but I recall some discussion somewhere saying that the history of the Squeak impl itself (not the name) traces back via saved base images to the original Smalltalk implementations, including via customs at-rest transformation tools when backwards incompatible changed where made in the primordial days. Base images, at least back when I was toying with Squeak, where never rebuilt from scratch, just modified, transformed etc. In some sense, at least for the image, they were decades old.

Yes. There is a direct path from modern Squeak to the original image from Smalltalk 78.

I've never implemented Squeak or any other Smalltalk.