the dda idea your using

[octanejohn]

alternative or more complex ideas
new rendering method from godot called hddagi godotengine/godot#86267
nanovdb library from openvdb called hdda
roma ray tracing
radiance cascades
amd brixelizer

[DouglasDwyer]

Thanks for the suggestions! I definitely want to learn about GI, so the Godot engine link looks particularly interesting.