Technote for the LPX-40 motherboard
I don't think this was ever used on a shipping product. It would have greatly limited disk compatibility which probably would have not been seen in a positive light.
That being said, browsing everymac shows about a billion Mac Clones where the only graphic evidence of existence is a tiny thumbnail from the 90s.
There's probably a ton of clones that were scrapped because they looked like boring PC stuff.
The Starmax that shipped had a bezel without a cutout for the eject button.
Even the various prototype CHRP Macs seemed to use a Mac/GCR floppy.
hey look, MacOS 7.6 for CHRP. one of two known copies of CHRP MacOS... neither archived
Unreleased CHRP StarMax
Another Motorola Viper CHRP prototype
Supposedly the Gossamer G3 logic board (as seen on the 'beige' G3s) also has a header for a PC-style MFM floppy drive... under the Mac floppy socket. I haven't confirmed this though, nor have I seen any pictures or evidence that it's ever been tested.