You might be interested in the recently announced Kickstarter which explores what might have been if Commodore hadn’t suffered from extraordinary management incompetence. It’s based on plans the actual people had at the time and seems like a fun read.
I often think about what the computing landscape would be like if some of these other companies had been more successful. The hard thing though is that most of them died so early in computing history, that we can't really know how they would have evolved. It's like imagining Windows 11 while using Windows 3.1. It's a shame there isn't a windows 11 like version of the Amiga OS, or something like GEOS with 30 extra years of development.