Sketchpad from 1963 would qualify.
In general, the framebuffer's ability to display "anything" is just too danged useful to make a GUI without it. Using a system without a framebuffer to make a GUI without needing much memory would mean that you need a very fast graphics processor, and that you have to accept limitations to the complexity of the user interface because you have to be able to draw every scanline within the time it takes to display that scanline.
Imagine, for example, the graphics of an NES. It has fixed tilesets, and a fixed number of dynamic sprites that can be displayed with the hardware in a frame. So, you can build a GUI on an NES, but you can't have arbitrarily many overlapping windows at arbitrary positions on that type of hardware the way you would expect on something like a Macintosh or an Amiga. If you tried, the graphics chip would have a potentially unbounded amount of work to do in a bounded amount of time to display that scanline, so it wouldn't work.
If you abandon a raster display and move to a vector display, you get much more flexibility in the timing budget for the UI. This is how Sketchpad worked. It used an oscilloscope as a vector monitor, rather than a TV style raster display. Thus, it could theoretically display arbitrarily complex onscreen drawings without a framebuffer, at the cost of an increasingly flickery image. There's a demo at this Youtube video: https://www.youtube.com/watch?v=hB3jQKGrJo0
Of course, the very first thing that Ivan Sutherland worked on after the Sketchpad vector UI was framebuffers. (He's the Sutherland in Evans and Sutherland, the company that sold the first commercial framebuffers.) Because having enough RAM for a raster image was obviously useful even in the earliest days of computer graphics.
In any event, the cost of custom vector displays, or custom hyperfast GPU processors, seemed impractical in the economics of the 1980's. RAM was expensive by modern standards, but GUI's of the time didn't use all that much of it. The original Macintosh famously only had 128 KB in 1984, and that was enough to be useful for real world GUI applications, and reasonably priced by the standards of the time.