It's got a very interesting pixel layout, different even from previous tandem OLEDs. Hard to describe quickly in words, but shown in Figure 2 here: https://www.apple.com/ca/macbook-pro/proled-xdr-display/pdf/... I imagine some of the C-shaped empty space is probably to accommodate the per-pixel emitter transistor.
This looks the same as the iPad Pro tandem OLED pixel layout. That I happen to write this comment on.
Doesn't the iPad Pro tandem OLED look like this? https://www.ltec-biz.com/en/report/post-3026/
The layout shown in that document is quite different.