There was quite a lot of early activity of course!
Essentially all of computer science academia was aware of the Xerox Alto, although it wasn't a commercial product and wasn't Unix.
Jim Morris left PARC and went off to CMU and began talking up the idea of the "3M" workstation. One MIPs, One Megabyte of RAM, and One Million Pixels.
One of the early commercial attempts was the Three Rivers PERC (or PERQ?) from the Pittsburgh startup. There were Unix adjacent systems as well, such as Apollo Domain.
Of course then Sun got started, and MIPS, and the IBM RT and VaxStations so by the mid '80s it was quite crowded.
There is a whole other arc about the graphics workstations, with SGI, Ardent, Stellar, Stardent, and so on.
Also, before graphics became affordable, there were various clustered character generator based systems like Convergent Technologies.
-L
It seems like there are bountiful articles able the decline and fall of the UNIX workstation, but I’ve had a hard time finding narrative about workstations prior to the Stanford SUN workstation.