It's a limitation of the M1 SOC. Either it's a limitation of the GPU or perhaps whichever bit of circuitry is required to translate screen buffers into HDMI or

It's a limitation of the M1 SOC. Either it's a limitation of the GPU or perhaps whichever bit of circuitry is required to translate screen buffers into HDMI or DisplayPort signals. I imagine that if/when Apple/AMD ever releases drivers for external PCI Express GPUs, it could be possible to attach a third or fourth display by way of a thunderbolt-attached external GPU enclosure. I'm unaware of any impediment to this aside from driver availability. But never, ever buy anything on the basis that future software updates might "fix" anything that frustrates you.