i would rather say that steve jobs's vision was to make the dynabook impossible; the central feature of the dynabook is that it is a tool for computational thinking for the masses, while the central feature of most of the designs of the projects jobs led (mac 128, imac, ipod, iphone, ipad—though not next) is that they're closed to the users, requiring special tools to open and modify that are only available to a chosen elite, and nowadays, even to write software for. it's a vision of society that sees it primarily as a market for products, not a community of intellectual collaboration or autonomous individual flourishing, which was the intent of the dynabook
the story of smalltalk at apple is fairly complex
apple did also implement smalltalk-80 on the lisa, and there's a screenshot of that in the smalltalk-80 book (01984), but it was apparently never released, even as proprietary software. apple shipped a macintosh smalltalk in august 01985 (according to http://basalgangster.macgui.com/RetroMacComputing/The_Long_V...) but i don't think squeak (the apple smalltalk that eventually became open-source) was derived from it
alan kay didn't join apple until 01984 (the year after jobs hired sculley as ceo), jobs left in september 01985, and squeak wasn't announced until 01996, which is about the time kay left, and i think squeak as a whole departed for disney at that point. jobs came back in 01997, and though he didn't kill squeak, he did kill hypercard, the other main environment for individual computational autonomy. jobs's apple did eventually make squeak open-source—in 02006!
jecel assumpçao in https://news.ycombinator.com/item?id=23392074 explains that the reason for finally open sourcing squeak a decade after the project ended was that olpc (itself fairly locked down, though less so than iphones) demanded it. also, though, he does heavily imply that it descended from the original apple smalltalk