You could sorta kinda claim that most OLED displays are not rectangular [1], since only green is at full resolution, with blue and red being at a partial resolution, by sharing those sub pixels between "logical" pixels.
Note for anyone confused, this is about AMOLED displays commonly used in phones and some OLED laptops from a few years ago.
W-OLED and QD-OLED have unconventional layouts compared to LCDs but every pixel has the complete set of sub pixels (RGB for QD-OLED, RGBW for W-OLED) so it looks more like this:
Just mentioning as while AMOLED phones being the majority of OLED displays seems plausible to me, it's likely not what people in this thread are picturing when they see OLED.
This feels like something else, it's ok if it has its own identity, otherwise it devolves/converges into a place to draw dicks in.