I never used that brand.   Xerox (which was the main USA supplier as a pure typewriter to compete with IBM's Selectric 'ball' units) were definitely fixed width.   People started to hack the Xerox units to add access to serial interface and Xerox made it standard or maybe an option as somepoint.     IIRC it was somebody like Ollivetti that originally did the daisywheel and Xerox licensed it and they definitely were the primary player here.  But by the late 70s, early 80's, there were a number of manufacturers of them.

My memory was with the maybe circa 74/75 timeframe, Xerox unit (but it might have been one of the others) was that the original unit had a serial port for diagnostics/maintenance which allowed access to the on-board microprocessor (which might have been a 4-bit TI chip IIRC - same used in some early 'Simon' games).   Somebody figured out how to hack it and the schematics/description was available.   I remember we hacked one of the units in the EE dept.    But by the late 1970's the serial interface was a first class part of the unit, which made them different from IBM Selectrics which did not have an easy to access serial interface, even though IBM used the printer mechanism from the Selectric as the guts of the console for the 360 which I think was called a 2150 but the bits in my brain on that are extremely stale.