I considered this, but I want it based on outside brightness, as it affects glare in the room. I’d like the blind to be open if at all possible, i.e. when it’s duller outside.

You must live near the equator where it’s always sunny and the sun always sets at the same time. As one moves near the poles the light shifts significantly with time and weather. Northern US States for example there could be light in the sky at 11p in the summer, and indistinguishable from midnight at 4:30p in the winter. If you get a particularly cloudy day or a smokey day you may need to turn on the lights to compensate.

Time is doable, but it’s pretty simplistic in terms of a set and forget home automation system to actually light and shade based on conditions which OP is asking for.