If the limitation is HDMI, then why do the MacBook M1 models only support ONE external display connected to TB / USB when there's multiple ( two ) TB ports? You could add a dongle for the power + extra display connection for two displays, but that configuration isn't supported. The issue is probably related to the M1 CPU.The limitation I’m referring to is one display has to be via hdmi.
so the 2018 intel mini is advertised as “up to 3” but only supports two if you use USB-c or tb or DisplayPort displays.
the 2020 m1 mini is advertised as “up to 2” but only supports one if you use USB-c or tb or DisplayPort displays.
Seems like your theory is incorrect.