I stayed up way too late tonight hunting and hunting for this. I remember it becasue I had it, and the internet is omniscient so the info *must* exist. My Red Bull fueled persistence paid off. After three hours of hunting, the word "prototoasters" popped to mind. That's what that 1-Bit toasters saver was called. Armed with that keyword I soon found an interview with After Dark creator Jack Eastman where he says Prototoasters was a module in After Dark 4.0 based on his original prototype artwork. Interview is here.
Then I found another page with images of both the prototoasters and the final, more familiar ones. Both in 1-Bit. Hopefully you can either chase down an old copy of After Dark 4 or use the 1-Bit images to create sprites. The images show the wings in both the up and down positions.
The prototoasters (and flying toast) in the 1-Bit image look exactly like the Prototoaster screensaver (except in After Dark they were DOS green in keeping with Berkeley Systems' motto "Agressively Stupid." :)
EDIT: After writing this I noticed that my second link is to ⌘GET INFO, the web site of gingerbeardman, who's developed several Playdate games (Daily Driver, Bender, Sparrow Solitaire, Circular, among others). He wrote at length about Tomoya Ikeda, the artist who created the 1-bit toaster artwork based onEastman's prototyping. So it stands to reason gingerbeardman would be on board with making the toasters fly on the Playdate via Stars of the Screen. Perhaps he could be of assistance.