I noticed this too, although on my system (Intel HD Graphics 5300) it seems to work with or without iris_dri.so. However, I also needed to patch SDL, because SDL's hardcoded pixel format (DRM_FORMAT_ARGB8888) is not supported.
I also noticed that it would be better to use 'dri_inst' here instead of 'copy_exec'; on amd64 just as on arm64, there are many *_dri.so files that are duplicates (hard links, actually.)
