Followup on last week's discovery that my 2015 13in MacBook Air (i7) running #OpenBSD amd64/7.5-stable actually supports a #4K external display and the discovery & purchase of the #OREI UHD-14VW #HDMI video wall controller (https://www.orei.com/products/hdmi-video-wall-controller-uhd-14vw) that supports combining my two #1080p HDMI displays for a single physical connection: it arrived today and I spent several hours installing & testing it. It works perfectly in 1x2 mode with a custom #3840x1080 #xrandr(1) mode added in #X11!