Probably only introduced the 24inch because of maximum pixel output limitation of M1. The 24inch is 4.5k and it supports one external display up to 6k. A 27”+ would require to push at least 5k (possibly 6k) for the internal monitor + 6k for the external For comparison the M1 Mac mini supports one 4K display and one 6k display. So it seems that this is close to the maximum for the M1 chip It also means that for us wit…
I doubt they would intentionally limit the internal resolution in order to obtain a high maximum external resolution.
They want to make sure their 6k display is supported across their entire lineup. Even the M1 Air supports it.